• Images
• Videos
• Documents
• Books
• Articles

Related Image Collections Add Image

Profiles

1 Image

We don't have any YouTube videos related to Halley's Comet yet.

You can add one yourself here.

We don't have any PDF documents related to Halley's Comet yet.

You can add one yourself here.

We don't have any Books related to Halley's Comet yet.

You can add one yourself here.

Archived Web Articles Add Article

Chaco Canyon mystery tour

Sep 18 2005

Much More Than Met the Eye

web.archive.org

Limits on the nucleus of Halley's Comet

nature.com

Comets: Mysterious Visitors from Outer Space

web.archive.org

Comets Breed Fear, Fascination and Web Sites

Mar 27 1997

TELESCOPE BUILDERS SEE HALLEY'S COMET FROM VERMONT HIILTOP

Aug 19 1985

Q&A

May 13 1985

Pronunciation

Comet Halley is usually pronounced /ˈhæli/, rhyming with valley, or sometimes /ˈheɪli/, rhyming with daily.³⁴ As to the surname Halley, Colin Ronan, one of Edmond Halley's biographers, preferred /ˈhɔːli/, rhyming with crawly.⁵ Spellings of Halley's name during his lifetime included Hailey, Haley, Hayley, Halley, Haly, Hawley, and Hawly, so its contemporary pronunciation is uncertain, but the version rhyming with valley seems to be preferred by current bearers of the surname.⁶

Computation of orbit

Halley was the first comet to be recognised as periodic. Until the Renaissance, the philosophical consensus on the nature of comets, promoted by Aristotle, was that they were disturbances in Earth's atmosphere. This idea was disproven in 1577 by Tycho Brahe, who used parallax measurements to show that comets must lie beyond the Moon. Many were still unconvinced that comets orbited the Sun, and assumed instead that they must follow straight paths through the Solar System.⁷ In 1687, Sir Isaac Newton published his Philosophiæ Naturalis Principia Mathematica, in which he outlined his laws of gravity and motion. His work on comets was decidedly incomplete. Although he had suspected that two comets that had appeared in succession in 1680 and 1681 were the same comet before and after passing behind the Sun (he was later found to be correct; see Newton's Comet),⁸ he was initially unable to completely reconcile comets into his model.⁹

Ultimately, it was Newton's friend, editor and publisher, Edmond Halley, who, in his 1705 Synopsis of the Astronomy of Comets, used Newton's new laws to calculate the gravitational effects of Jupiter and Saturn on cometary orbits.¹⁰ Having compiled a list of 24 comet observations, he calculated that the orbital elements of a second comet that had appeared in 1682 were nearly the same as those of two comets that had appeared in 1531 (observed by Petrus Apianus) and 1607 (observed by Johannes Kepler).¹¹ Halley thus concluded that all three comets were the same object returning about every 76 years, a period that has since been found to vary between 72 and 80 years.¹² After a rough estimate of the perturbations the comet would sustain from the gravitational attraction of the planets, he predicted its return for 1758.¹³ He had personally observed the comet around perihelion in September 1682,¹⁴ but died in 1742 before he could observe its predicted return.¹⁵

Halley's prediction of the comet's return proved to be correct, although it was not seen until 25 December 1758, by Johann Georg Palitzsch, a German farmer and amateur astronomer. Other observers from throughout Europe and its colonies sent confirmations to Paris after the comet brightened early the following year. In the Americas, John Winthrop lectured at Harvard University to explain the implications of the comet's reappearance for Newtonian mechanics and natural theology.¹⁶

Another independent recognition that the comet had returned was made by the Jamaican astronomer Francis Williams, but his observations did not reach Europe.¹⁷¹⁸ A unique portrait commissioned by Williams demonstrates the impact of the comet's return on period astronomers. Williams' hand rests on page 521 of the third edition of Newton's Principia with procedures to predict comet sightings. The white smudge in the sky is probably a depiction of Halley's comet relative to the constellations in March 1759, and the chord hanging above the book likely represents the comet's orbit.¹⁹²⁰ In 2024, using X-ray imaging, the painting was shown to depict the field of stars in which the comet would have been visible in 1759. Williams likely commissioned the portrait to commemorate his observations.²¹

The comet did not pass through its perihelion until 13 March 1759, the attraction of Jupiter and Saturn having caused a delay of 618 days.²² This effect was computed before its return (with a one-month error to 13 April)²³ by a team of three French mathematicians, Alexis Clairaut, Joseph Lalande, and Nicole-Reine Lepaute.²⁴ The confirmation of the comet's return was the first time anything other than planets had been shown to orbit the Sun.²⁵ It was also one of the earliest successful tests of Newtonian physics, and a clear demonstration of its explanatory power.²⁶ The comet was first named in Halley's honour by French astronomer Nicolas-Louis de Lacaille in 1759.²⁷

Some scholars have proposed that first-century Mesopotamian astronomers already had recognised Halley's Comet as periodic.²⁸ This theory notes a passage in the Babylonian Talmud, tractate Horayot²⁹ that refers to "a star which appears once in seventy years that makes the captains of the ships err".³⁰ It has also been suggested that the passage may have referred to the variable star Mira, whose brightness oscillates with a period of sixty years.³¹

Researchers in 1981 attempting to calculate the past orbits of Halley by numerical integration starting from accurate observations in the seventeenth and eighteenth centuries could not produce accurate results further back than 837 owing to a close approach to Earth in that year. It was necessary to use ancient Chinese comet observations to constrain their calculations.³²

Orbit and origin

Halley's orbital period has varied between 74 and 80 years since 240 BC.³³ Its orbit around the Sun is highly elliptical, with an orbital eccentricity of 0.967 (with 0 being a circle and 1 being a parabolic trajectory). The perihelion, the point in the comet's orbit when it is nearest the Sun, is 0.59 au (88 million km). This is between the orbits of Mercury and Venus. Its aphelion, or farthest distance from the Sun, is 35 au (5.2 billion km), roughly the orbital distance of Pluto. Unlike the overwhelming majority of objects in the Solar System, Halley's orbit is retrograde; it orbits the Sun in the opposite direction to the planets, or, clockwise from above the Sun's north pole.³⁴ The orbit is inclined by 18° to the ecliptic, with much of it lying south of the ecliptic.³⁵ This is usually represented as 162°, to account for Halley's retrograde orbit.³⁶³⁷ The 1910 passage was at a relative velocity of 70.56 km/s (157,800 mph).³⁸ Because its orbit comes close to Earth's in two places, Halley is associated with two meteor showers: the Eta Aquariids in early May, and the Orionids in late October.³⁹

Halley is classified as a periodic or short-period comet: one with an orbit lasting 200 years or less.⁴⁰ This contrasts it with long-period comets, whose orbits last for thousands of years. Periodic comets have an average inclination to the ecliptic of only ten degrees, and an orbital period of just 6.5 years, so Halley's orbit is atypical.⁴¹ Most short-period comets (those with orbital periods shorter than 20 years and inclinations of 30 degrees or less) are called Jupiter-family comets.⁴² Those resembling Halley, with orbital periods of between 20 and 200 years and inclinations extending from zero to more than 90 degrees, are called Halley-type comets.⁴³⁴⁴ As of 2024, 105 Halley-type comets have been observed, compared with 816 identified Jupiter-family comets.⁴⁵⁴⁶

The orbits of the Halley-type comets suggest that they were originally long-period comets whose orbits were perturbed by the gravity of the giant planets and directed into the inner Solar System.⁴⁷ If Halley was once a long-period comet, it is likely to have originated in the Oort cloud,⁴⁸ a sphere of cometary bodies around 20,000–50,000 au from the Sun. Conversely the Jupiter-family comets are generally believed to originate in the Kuiper belt,⁴⁹ a flat disc of icy debris between 30 au (Neptune's orbit) and 50 au from the Sun (in the scattered disc). Another point of origin for the Halley-type comets was proposed in 2008, when a trans-Neptunian object with a retrograde orbit similar to Halley's was discovered, 2008 KV42, whose orbit takes it from just outside that of Uranus to twice the distance of Pluto. It may be a member of a new population of small Solar System bodies that serves as the source of Halley-type comets.⁵⁰

Halley has probably been in its current orbit for 16,000–200,000 years, although it is not possible to numerically integrate its orbit for more than a few tens of apparitions, and close approaches before 837 AD can only be verified from recorded observations.⁵¹ The non-gravitational effects can be crucial;⁵² as Halley approaches the Sun, it expels jets of sublimating gas from its surface, which knock it very slightly off its orbital path. These orbital changes cause delays in its perihelion passage of four days on average.⁵³

In 1989, Boris Chirikov and Vitold Vecheslavov performed an analysis of 46 apparitions of Halley's Comet taken from historical records and computer simulations, which showed that its dynamics were chaotic and unpredictable on long timescales.⁵⁴ Halley's projected dynamical lifetime is estimated to be about 10 million years.⁵⁵ The dynamics of its orbit can be approximately described by a two-dimensional symplectic map, known as the Kepler map, a solution to the restricted three-body problem for highly eccentric orbits.⁵⁶⁵⁷ Based on records from the 1910 apparition, David Hughes calculated in 1985 that Halley's nucleus has been reduced in mass by 80 to 90% over the last 2,000 to 3,000 revolutions, and that it will most likely disappear completely after another 2,300 perihelion passages.⁵⁸ More recent work suggests that Halley will evaporate, or split in two, within the next few tens of thousands of years, or will be ejected from the Solar System within a few hundred thousand years.⁵⁹⁶⁰

Structure and composition

The Giotto and Vega missions gave planetary scientists their first view of Halley's surface and structure. The nucleus is a conglomerate of ices and dust, often referred to as a "dirty snowball".⁶¹ Like all comets, as Halley nears the Sun, its volatile compounds (those with low boiling points, such as water, carbon monoxide, carbon dioxide and other ices) begin to sublimate from the surface.⁶² This causes the comet to develop a coma, or atmosphere, at distances up to 230,000 kilometres (140,000 mi) from the nucleus.⁶³ Sublimation of this dirty ice releases dust particles, which travel with the gas away from the nucleus. Gas molecules in the coma absorb solar light and then re-radiate it at different wavelengths, a phenomenon known as fluorescence, whereas dust particles scatter the solar light. Both processes are responsible for making the coma visible.⁶⁴ As a fraction of the gas molecules in the coma are ionised by the solar ultraviolet radiation,⁶⁵ pressure from the solar wind, a stream of charged particles emitted by the Sun, pulls the coma's ions out into a long tail, which may extend more than 100 million kilometres into space.⁶⁶⁶⁷ Changes in the flow of the solar wind can cause disconnection events, in which the tail completely breaks off from the nucleus.⁶⁸

Despite the vast size of its coma, Halley's nucleus is relatively small: barely 15 kilometres (9.3 mi) long, 8 kilometres (5.0 mi) wide and perhaps 8 kilometres (5.0 mi) thick.⁶⁹⁷⁰ Based on a reanalysis of images taken by the Giotto and Vega spacecraft, Lamy et al. determined an effective diameter of 11 kilometres (6.8 mi).⁷¹⁷² Its shape has been variously compared to that of a peanut, a potato, or an avocado.⁷³ Its mass is roughly 2.2 × 1014 kg,⁷⁴ with an average density of about 0.55 grams per cubic centimetre (0.32 oz/cu in).⁷⁵ The low density indicates that it is made of a large number of small pieces, held together very loosely, forming a structure known as a rubble pile.⁷⁶ Ground-based observations of coma brightness suggested that Halley's rotation period was about 7.4 days. Images taken by the various spacecraft, along with observations of the jets and shell, suggested a period of 52 hours.⁷⁷⁷⁸ Given the irregular shape of the nucleus, Halley's rotation is likely to be complex.⁷⁹ The flyby images revealed an extremely varied topography, with hills, mountains, ridges, depressions, and at least one crater.⁸⁰

Halley's day side (the side facing the Sun) is far more active than the night side.⁸¹ Spacecraft observations showed that the gases ejected from the nucleus were 80% water vapour, 17% carbon monoxide and 3–4% carbon dioxide,⁸² with traces of hydrocarbons⁸³ although more recent sources give a value of 10% for carbon monoxide and also include traces of methane and ammonia.⁸⁴ The dust particles were found to be primarily a mixture of carbon–hydrogen–oxygen–nitrogen (CHON) compounds common in the outer Solar System, and silicates, such as are found in terrestrial rocks.⁸⁵ The dust particles ranged in size down to the limits of detection (≈0.001 μm).⁸⁶ The ratio of deuterium to hydrogen in the water released by Halley was initially thought to be similar to that found in Earth's ocean water, suggesting that Halley-type comets may have delivered water to Earth in the distant past. Subsequent observations showed Halley's deuterium ratio to be far higher than that found in Earth's oceans, making such comets unlikely sources for Earth's water.⁸⁷

Giotto provided the first evidence in support of Fred Whipple's "dirty snowball" hypothesis for comet construction; Whipple postulated that comets are icy objects warmed by the Sun as they approach the inner Solar System, causing ices on their surfaces to sublime (change directly from a solid to a gas), and jets of volatile material to burst outward, creating the coma. Giotto showed that this model was broadly correct,⁸⁸ though with modifications. Halley's albedo, for instance, is about 4%, meaning that it reflects only 4% of the sunlight hitting it – about what one would expect for coal.⁸⁹ Thus, despite astronomers predicting that Halley would have an albedo of about 0.17 (roughly equivalent to bare soil), Halley's Comet is in fact pitch black.⁹⁰ The "dirty ices" on the surface sublime at temperatures between 170 K (−103 °C) in sections of higher albedo to 220 K (−53 °C) at low albedo; Vega 1 found Halley's surface temperature to be in the range 300–400 K (27–127 °C). This suggested that only 10% of Halley's surface was active, and that large portions of it were coated in a layer of dark dust that retained heat.⁹¹ Together, these observations suggested that Halley was in fact predominantly composed of non-volatile materials, and thus more closely resembled a "snowy dirtball" than a "dirty snowball".⁹²⁹³

History

Before 1066

Due to its intrinsic brightness, about one eighth of all comet sightings mentioned in historic records belong to Halley's Comet.⁹⁴ The first certain appearance of Halley's Comet in the historical record is a description from 240 BC, in the Chinese chronicle Records of the Grand Historian or Shiji, which describes a comet that appeared in the east and moved north.⁹⁵ The only surviving record of the 164 BC apparition is found on two fragmentary Babylonian tablets, which were rediscovered in August 1984 in the collection of the British Museum.⁹⁶⁹⁷

The apparition of 87 BC was recorded in Babylonian tablets which state that the comet was seen "day beyond day" for a month.⁹⁸ This appearance may be recalled in the representation of Tigranes the Great, an Armenian king who is depicted on coins with a crown that features, according to Vahe Gurzadyan and R. Vardanyan, "a star with a curved tail [that] may represent the passage of Halley's Comet in 87 BC." Gurzadyan and Vardanyan argue that "Tigranes could have seen Halley's Comet when it passed closest to the Sun on August 6 in 87 BC" as the comet would have been a "most recordable event"; for ancient Armenians it could have heralded the New Era of the brilliant King of Kings.⁹⁹

The apparition of 12 BC was recorded in the Book of Han by Chinese astronomers of the Han dynasty who tracked it from August through October.¹⁰⁰ It passed within 0.16 au of Earth.¹⁰¹ According to the Roman historian Cassius Dio, a comet appeared suspended over Rome for several days portending the death of Marcus Vipsanius Agrippa in that year.¹⁰² Halley's appearance in 12 BC, only a few years distant from the conventionally assigned date of the birth of Jesus Christ, has led some theologians and astronomers to suggest that it might explain the biblical story of the Star of Bethlehem. There are other explanations for the phenomenon, such as planetary conjunctions, and there are also records of other comets that appeared closer to the date of Jesus's birth.¹⁰³

If Yehoshua ben Hananiah's reference to "a star which arises once in seventy years and misleads the sailors"¹⁰⁴ refers to Halley's Comet, he can only have witnessed the 66 AD appearance.¹⁰⁵ Another possible report comes from Jewish historian Josephus,¹⁰⁶ who wrote that in 66 AD "The signs ... were so evident, and did so plainly foretell their future desolation ... there was a star resembling a sword, which stood over the city, and a comet, that continued a whole year".¹⁰⁷¹⁰⁸ This portent was in reference to the city of Jerusalem and the First Jewish–Roman War.¹⁰⁹

The 141 AD apparition was recorded in Chinese chronicles, with observations of a bluish white comet on 27 March and 16, 22 and 23 April.¹¹⁰ The early Tamil bards of southern India (c. 1st - 4th century CE) also describe a certain relatable event.¹¹¹

The 374 AD and 607 approaches each came within 0.09 au of Earth.¹¹² The 451 AD apparition was said to herald the defeat of Attila the Hun at the Battle of Chalons.¹¹³¹¹⁴

The 684 AD apparition was reported in Chinese records as the "broom star".¹¹⁵

The 760 AD apparition was recorded in the Zuqnin Chronicle's entry for iyyōr 1071 SE (May 760 AD), calling it a "white sign":¹¹⁶

The year [SE] one thousand seventy one (AD 759/760).

In the month of iyyōr (May) a white sign was seen in the sky, before early twilight, in the north-east [quarter], in the Zodiac [sign] which is called Aries, to the north from these three stars in it, which are very shining. And it resembled in its shape a broom [...]

And the sign itself remained for fifteen nights, until dawn of the feast of Pentecost.

— Zuqnin Chronicle, fol.136v; Neuhäuser et al. (trans.)

In 837 AD, Halley's Comet may have passed as close as 0.03 astronomical units (2.8 million miles; 4.5 million kilometres) from Earth, by far its closest approach.¹¹⁷¹¹⁸ Its tail may have stretched 60 degrees across the sky. It was recorded by astronomers in China, Japan, Germany, the Byzantine Empire, and the Middle East;¹¹⁹ Emperor Louis the Pious observed this appearance and devoted himself to prayer and penance, fearing that "by this token a change in the realm and the death of a prince are made known".¹²⁰

In 912 AD, Halley is recorded in the Annals of Ulster, which states "A dark and rainy year. A comet appeared."¹²¹

1066

In 1066, the comet was seen in England and thought to be an omen: later that year Harold II of England died at the Battle of Hastings and William the Conqueror claimed the throne. The comet is represented on the Bayeux Tapestry and described in the tituli as a star. Surviving accounts from the period describe it as appearing to be four times the size of Venus, and shining with a light equal to a quarter of that of the Moon. Halley came within 0.10 au of Earth at that time.¹²²

This appearance of the comet is also noted in the Anglo-Saxon Chronicle. Eilmer of Malmesbury may have seen Halley in 989 and 1066, as recorded by William of Malmesbury:

Not long after, a comet, portending (they say) a change in governments, appeared, trailing its long flaming hair through the empty sky: concerning which there was a fine saying of a monk of our monastery called Æthelmær. Crouching in terror at the sight of the gleaming star, "You've come, have you?", he said. "You've come, you source of tears to many mothers. It is long since I saw you; but as I see you now you are much more terrible, for I see you brandishing the downfall of my country."¹²³

The Irish Annals of the Four Masters recorded the comet as "A star [that] appeared on the seventh of the Calends of May, on Tuesday after Little Easter, than whose light the brilliance or light of The Moon was not greater; and it was visible to all in this manner till the end of four nights afterwards."¹²⁴ Chaco Native Americans in New Mexico may have recorded the 1066 apparition in their petroglyphs.¹²⁵

The Italo-Byzantine chronicle of Lupus the Protospatharios mentions that a "comet-star" appeared in the sky in the year 1067 (the chronicle is erroneous, as the event occurred in 1066, and by Robert he means William).

The Emperor Constantine Ducas died in the month of May, and his son Michael received the Empire. And in this year there appeared a comet star, and the Norman count Robert [sic] fought a battle with Harold, King of the English, and Robert was victorious and became king over the people of the English.¹²⁶

1145–1378

The 1145 apparition may have been recorded by the monk Eadwine.¹²⁷

According to legend, Genghis Khan was inspired to turn his conquests toward Europe by the westward-seeming trajectory of the 1222 apparition.¹²⁸¹²⁹ In Korea, the comet was reportedly visible during the daylight on 9 September 1222.¹³⁰

The 1301 apparition was visually spectacular, and may be the first that resulted in convincing portraits of a particular comet. The Florentine chronicler Giovanni Villani wrote that the comet left "great trails of fumes behind", and that it remained visible from September 1301 until January 1302.¹³¹¹³² It was seen by the artist Giotto di Bondone, who represented the Star of Bethlehem as a fire-coloured comet in the Nativity section of his Arena Chapel cycle, completed in 1305. Giotto's depiction includes details of the coma, a sweeping tail, and the central condensation. According to the art historian Roberta Olson, it is much more accurate than other contemporary descriptions, and was not equaled in painting until the 19th century.¹³³¹³⁴ Olson's identification of Halley's Comet in Giotto's Adoration of the Magi is what inspired the European Space Agency to name their mission to the comet Giotto, after the artist.¹³⁵

Halley's 1378 appearance is recorded in the Annales Mediolanenses¹³⁶ as well as in East Asian sources.¹³⁷

1456

In 1456, the year of Halley's next apparition, the Ottoman Empire invaded the Kingdom of Hungary, culminating in the siege of Belgrade in July of that year. In a papal bull, Pope Callixtus III ordered special prayers be said for the city's protection. In 1470, the humanist scholar Bartolomeo Platina wrote in his Lives of the Popes [la] that,¹³⁸

A hairy and fiery star having then made its appearance for several days, the mathematicians declared that there would follow grievous pestilence, dearth and some great calamity. Calixtus, to avert the wrath of God, ordered supplications that if evils were impending for the human race He would turn all upon the Turks, the enemies of the Christian name. He likewise ordered, to move God by continual entreaty, that notice should be given by the bells to call the faithful at midday to aid by their prayers those engaged in battle with the Turk.

Platina's account is not mentioned in official records. In the 18th century, a Frenchman further embellished the story, in anger at the Church, by claiming that the Pope had "excommunicated" the comet, though this story was most likely his own invention.¹³⁹

Halley's apparition of 1456 was also witnessed in Kashmir and depicted in great detail by Śrīvara, a Sanskrit poet and biographer to the Sultans of Kashmir. He read the apparition as a cometary portent of doom foreshadowing the imminent fall of Sultan Zayn al-Abidin (AD 1418/1420–1470).¹⁴⁰

After witnessing a bright light in the sky which most historians have identified as Halley's Comet, Zara Yaqob, Emperor of Ethiopia from 1434 to 1468, founded the city of Debre Berhan (tr. City of Light) and made it his capital for the remainder of his reign.¹⁴¹

1531-1759

In the Sikh scriptures of the Guru Granth Sahib, the founder of the faith Guru Nanak makes reference to "a long star that has risen" at Ang 1110, and it is believed by some Sikh scholars to be a reference to Halley's appearance in 1531.¹⁴²

Halley's periodic returns have been subject to scientific investigation since the 16th century. Petrus Apianus and Girolamo Fracastoro described the comet's visit in 1531, with the former even including graphics in his publication. Through his observations, Apianus was able to prove that a comet's tail always points away from the Sun.¹⁴³ The three apparitions from 1531 to 1682 were noted by Edmond Halley, enabling him to predict it would return.¹⁴⁴ One key breakthrough occurred when Halley talked with Newton about his ideas of the laws of motion. Newton also helped Halley get John Flamsteed's data on the 1682 apparition.¹⁴⁵ By studying data on the 1531, 1607, and 1682 comets, he came to the conclusion these were the same comet, and presented his findings in 1696.¹⁴⁶

One difficulty was accounting for variations in the comet's orbital period, which was over a year longer between 1531 and 1607 than it was between 1607 and 1682.¹⁴⁷ Newton had theorised that such delays were caused by the gravity of other comets, but Halley found that Jupiter and Saturn would cause the appropriate delays.¹⁴⁸ In the decades that followed, more refined mathematics would be worked on, notable by Paris Observatory; the work on Halley also provided a boost to Newton and Kepler's rules for celestial motions.¹⁴⁹ (See also computation of orbit.)

1835

At Markree Observatory in Ireland, Edward Joshua Cooper used a Cauchoix of Paris lens telescope with an aperture of 340 millimetres (13.3 in) to sketch Halley's comet in 1835.¹⁵⁰ The same apparition was sketched by German astronomer Friedrich Wilhelm Bessel.¹⁵¹ Observations of streams of vapour prompted Bessel to propose that the jet forces of evaporating material could be great enough to significantly alter a comet's orbit.¹⁵²

An interview in 1910, of someone who was a teenager at the time of the 1835 apparition had this to say:¹⁵³

When the comet was first seen, it appeared in the western sky, its head toward the north and tail towards the south, about horizontal and considerably above the horizon and quite a distance south of the Sun. It could be plainly seen directly after sunset every day, and was visible for a long time, perhaps a month ...

They go on to describe the comet's tail as being more broad and not as long as the comet of 1843 they had also witnessed.¹⁵⁴

Famous astronomers across the world made observations starting August 1835, including Struve at Dorpat observatory, and Sir John Herschel, who made of observations from the Cape of Good Hope.¹⁵⁵ In the United States telescopic observations were made from Yale College.¹⁵⁶ The new observations helped confirm early appearances of this comet including its 1456 and 1378 apparitions.¹⁵⁷

At Yale College in Connecticut, the comet was first reported on 31 August 1835 by astronomers D. Olmstead and E. Loomis.¹⁵⁸ In Canada reports were made from Newfoundland and also Quebec.¹⁵⁹ Reports came in from all over by later 1835, and often reported in newspapers of this time in Canada.¹⁶⁰

Several accounts of the 1835 apparition were made by observers who survived until the 1910 return, where increased interest in the comet led to their being interviewed.¹⁶¹

The time to Halley's return in 1910 would be only 74.42 years, one of the shortest known periods of its return, which is calculated to be as long as 79 years owing to the effects of the planets.¹⁶²

At Paris Observatory Halley's Comet 1835 apparition was observed with a Lerebours telescope of 24.4 cm (9.6 in) aperture by the astronomer François Arago.¹⁶³ Arago recorded polarimetric observations of Halley, and suggested that the tail might be sunlight reflecting off a sparsely distributed material; he had earlier made similar observations of Comet Tralles of 1819.¹⁶⁴

1910

The 1910 approach, which came into naked-eye view around 10 April¹⁶⁵ and came to perihelion on 20 April,¹⁶⁶ was notable for several reasons: it was the first approach of which photographs exist, and the first for which spectroscopic data were obtained.¹⁶⁷ Furthermore, the comet made a relatively close approach of 0.15 au,¹⁶⁸ making it a spectacular sight. Indeed, on 19 May, Earth actually passed through the tail of the comet.¹⁶⁹¹⁷⁰ One of the substances discovered in the tail by spectroscopic analysis was the toxic gas cyanogen,¹⁷¹ which led press to misquote the astronomer Camille Flammarion by stating he claimed that, when Earth passed through the tail, the gas "would impregnate the atmosphere and possibly snuff out all life on the planet".¹⁷²¹⁷³ Despite reassurances from scientists that the gas would not inflict harm on Earth,¹⁷⁴ the damage had already been done with members of the public panic buying gas masks and quack "anti-comet pills".¹⁷⁵

The comet added to the unrest in China on the eve of the Xinhai Revolution that would end the last dynasty in 1911.¹⁷⁶ As James Hutson, a missionary in Sichuan Province at the time, recorded:

"The people believe that it indicates calamity such as war, fire, pestilence, and a change of dynasty. In some places on certain days the doors were unopened for half a day, no water was carried and many did not even drink water as it was rumoured that pestilential vapour was being poured down upon the earth from the comet."¹⁷⁷

The 1910 visitation coincided with a visit from Hedley Churchward, the first known English Muslim to make the Haj pilgrimage to Mecca.¹⁷⁸

The comet was used in an advertising campaign of Le Bon Marché, a well-known department store in Paris.¹⁷⁹

The comet was also fertile ground for hoaxes. One that reached major newspapers claimed that the Sacred Followers, a supposed Oklahoma religious group, attempted to sacrifice a virgin to ward off the impending disaster, but were stopped by the police.¹⁸⁰

American satirist and writer Mark Twain was born on 30 November 1835, exactly two weeks after the comet's perihelion. In his autobiography, published in 1909, he said,

I came in with Halley's comet in 1835. It is coming again next year, and I expect to go out with it. It will be the greatest disappointment of my life if I don't go out with Halley's comet. The Almighty has said, no doubt: "Now here are these two unaccountable freaks; they came in together, they must go out together."¹⁸¹¹⁸²

Twain died on 21 April 1910, the day following the comet's subsequent perihelion.¹⁸³¹⁸⁴ The 1985 fantasy film The Adventures of Mark Twain was inspired by the quotation.¹⁸⁵

Halley's 1910 apparition is distinct from the Great Daylight Comet of 1910, which surpassed Halley in brilliance and was visible in broad daylight for a short period, approximately four months before Halley made its appearance.¹⁸⁶¹⁸⁷

1986

The 1986 apparition of Halley's Comet was the least favourable on record. In February 1986, the comet and the Earth were on opposite sides of the Sun, creating the worst possible viewing circumstances for Earth observers during the previous 2,000 years.¹⁸⁸ Halley's closest approach was 0.42 au.¹⁸⁹ Additionally, increased light pollution from urbanisation caused many people to fail in attempts to see the comet. With the help of binoculars, observation from areas outside cities was more successful.¹⁹⁰ Further, the comet appeared brightest when it was almost invisible from the northern hemisphere in March and April 1986,¹⁹¹ with best opportunities occurring when the comet could be sighted close to the horizon at dawn and dusk, if not obscured by clouds.

The approach of the comet was first detected by astronomers David C. Jewitt and G. Edward Danielson on 16 October 1982 using the 5.1 m Hale Telescope at Mount Palomar and a CCD camera.¹⁹²

The first visual observation of the comet on its 1986 return was by an amateur astronomer, Stephen James O'Meara, on 24 January 1985. O'Meara used a home-built 610-millimetre (24 in) telescope on top of Mauna Kea to detect the magnitude 19.6 comet.¹⁹³ The first to observe Halley's Comet with the naked eye during its 1986 apparition were Stephen Edberg (then serving as the coordinator for amateur observations at the NASA Jet Propulsion Laboratory) and Charles Morris on 8 November 1985.¹⁹⁴

The 1986 apparition gave scientists the opportunity to study the comet closely, and several probes were launched to do so. The Soviet Vega 1 probe began returning images of Halley on 4 March 1986, captured the first-ever image of its nucleus,¹⁹⁵ and made its flyby on 6 March. It was followed by the Vega 2 probe, making its flyby on 9 March. On 14 March, the Giotto space probe, launched by the European Space Agency, made the closest pass of the comet's nucleus.¹⁹⁶ There also were two Japanese probes, Suisei and Sakigake. Unofficially, the numerous probes became known as the Halley Armada.¹⁹⁷

Based on data retrieved by the largest ultraviolet space telescope of the time, Astron, in December 1985, a group of Soviet scientists developed a model of the comet's coma.¹⁹⁸ The comet also was observed from space by the International Cometary Explorer (ICE). Originally launched as the International Sun-Earth Explorer 3, the spacecraft was renamed, and departed the Sun-Earth L1 Lagrangian point in 1982 in order to intercept the comets 21P/Giacobini-Zinner and Halley.¹⁹⁹ ICE flew through the tail of Halley's Comet, coming within about 40.2 million km (25.0 million mi) of the nucleus on 28 March 1986.²⁰⁰²⁰¹

Two U.S. Space Shuttle missions—STS-51-L and STS-61-E—had been scheduled to observe Halley's Comet from low Earth orbit. The STS-51-L mission carried the Shuttle-Pointed Tool for Astronomy (Spartan Halley) satellite, also called the Halley's Comet Experiment Deployable (HCED).²⁰² The mission to capture the ultraviolet spectrum of the comet ended in disaster when the Space Shuttle Challenger disintegrated in flight, killing all seven astronauts onboard.²⁰³ Scheduled for March 1986, STS-61-E was a Columbia mission carrying the ASTRO-1 platform to study the comet,²⁰⁴ but the mission was cancelled following the Challenger disaster and ASTRO-1 would not fly until late 1990 on STS-35.²⁰⁵

In Japan, the comet was observed by Emperor Hirohito, who was 84.²⁰⁶ He had already seen it in 1910 when he was 8.²⁰⁷

After 1986

On 12 February 1991, at a distance of 14.3 au (2.14×109 km) from the Sun, Halley displayed an outburst that lasted for several months.²⁰⁸²⁰⁹ The comet released dust with a total mass of about 108 kg, which spread into an elongated cloud roughly 374,000 km (232,000 mi) by 269,000 km (167,000 mi) in size.²¹⁰ The outburst likely started in December 1990, and then the comet brightened from about magnitude 25 to magnitude 19.²¹¹²¹² Comets rarely show outburst activity at distances beyond 5 au from the Sun.²¹³ Different mechanisms have been proposed for the outburst, ranging from interaction with the solar wind to a collision with an undiscovered asteroid.²¹⁴ The most likely explanation is a combination of two effects, the polymerisation of hydrogen cyanide and a phase transition of amorphous water ice, which raised the temperature of the nucleus enough for some of the more volatile compounds on its surface to sublime.²¹⁵

Halley was most recently observed in 2003 by three of the Very Large Telescopes at Paranal, Chile, when Halley's magnitude was 28.2. The telescopes observed Halley, at the faintest and farthest any comet had ever been imaged, in order to verify a method for finding very faint trans-Neptunian objects.²¹⁶ Astronomers are now able to observe the comet at any point in its orbit.²¹⁷

On 9 December 2023, Halley's Comet reached the farthest and slowest point in its orbit from the Sun when it was travelling at 0.91 km/s (2,000 mph) with respect to the Sun.²¹⁸²¹⁹

2061

The next perihelion of Halley's Comet is predicted for 28 July 2061,²²⁰²²¹ when it will be better positioned for observation than during the 1985–1986 apparition, as it will be on the same side of the Sun as Earth.²²² The closest approach to Earth will be one day after perihelion.²²³ It is expected to have an apparent magnitude of −0.3, compared with only +2.1 for the 1986 apparition.²²⁴ On 9 September 2060, Halley will pass within 0.98 au (147,000,000 km) of Jupiter, and then on 20 August 2061 will pass within 0.0543 au (8,120,000 km) of Venus.²²⁵

2134

Halley will come to perihelion on 27 March 2134.²²⁶²²⁷ Then on 7 May 2134, Halley will pass within 0.092 au (13,800,000 km) of Earth.²²⁸ Its apparent magnitude is expected to be −2.0.²²⁹

Apparitions

Halley's calculations enabled the comet's earlier appearances to be found in the historical record. The following table sets out the astronomical designations for every apparition of Halley's Comet from 240 BC, the earliest documented sighting.²³⁰²³¹

In the designations, "1P/" refers to Halley's Comet; the first periodic comet discovered. The number represents the year, with negatives representing BC. The letter-number combination indicates which it was of the comets observed for a given segment of the year, divided into 24 equal parts.²³² The Roman numeral indicates which comet past perihelion it was for a given year, while the lower-case letter indicates which comet it was for a given year overall.²³³ The perihelion dates farther from the present are approximate, mainly because of uncertainties in the modelling of non-gravitational effects. Perihelion dates of 1531 and earlier are in the Julian calendar, while perihelion dates 1607 and after are in the Gregorian calendar.²³⁴ The perihelion dates for some of the early apparitions (particularly before 837 AD) are uncertain by a couple of days.²³⁵ While Halley's Comet usually peaks at around 0th magnitude, there are indications that the comet got considerably brighter than that in the past.²³⁶

See also

• Kepler orbit
• List of Halley-type comets

Notes

Bibliography

• Goodrich, Richard J. (2023). Comet Madness. How the 1910 Return of Halley's Comet (Almost) Destroyed Civilization. Prometheus Books. p. 188. ISBN 9781633888579.
• Grier, David Alan (2005). "The First Anticipated Return: Halley's Comet 1758". When Computers Were Human. Princeton: Princeton University Press. ISBN 0-691-09157-9.
• Kronk, Gary W. (1999). Cometography, vol. 1: Ancient-1799. Cambridge University Press. ISBN 978-0-521-58504-0.
• Lancaster-Brown, Peter (1985). Halley & His Comet. Blandford Press. ISBN 0-7137-1447-6.
• Lequeux, James (2015). François Arago: A 19th Century French Humanist and Pioneer in Astrophysics. Springer. ISBN 978-3-319-20723-0.
• Milbrath, Susan (1999). Star Gods of the Maya: Astronomy in Art, Folklore, and Calendars. The Linda Schele Series in Maya and Pre-Columbian Studies. University of Texas Press. doi:10.7560/752252. ISBN 978-0-292-79793-2.
• Needham, Joseph (1959). "Comets, meteors, and meteorites". Science and Civilisation in China: Volume 3, Mathematics and the Sciences of the Heavens and the Earth. Cambridge University Press. pp. 430–433. ISBN 978-0-521-05801-8. {{cite book}}: ISBN / Date incompatibility (help)
• Rayner, John D. (1998). A Jewish Understanding of the World. Berghahn Books. pp. 108–111. ISBN 1-57181-973-8.
• Sagan, Carl; Druyan, Ann (1985). Comet. Random House. ISBN 0-394-54908-2.
• Schmude, Richard M. (2010). Comets and How to Observe Them. Springer. p. 3. ISBN 978-1-4419-5790-0.
• Shayler, David J.; Burgess, Colin (2007). "Ending of Eras". NASA's Scientist-Astronauts. Praxis. ISBN 978-0-387-21897-7. Retrieved 7 January 2009.
• Siddiqi, Asif A. (2018). Beyond Earth: A Chronicle of Deep Space Exploration. United States: NASA History Program Office. pp. 149–150. ISBN 9781626830424.
• Yeomans, Donald Keith (1991). Comets: A Chronological History of Observation, Science, Myth, and Folklore. Wiley and Sons. pp. 260–261. ISBN 0-471-61011-9.

External links

• 1P/Halley at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters
• Synopsis of the Astronomy of Comets (1706 reprint of Halley's 1705 paper)
• Image of Halley's Comet by the Giotto spacecraft
• seds.org, links to images and further information about Halley's Comet
• Photographs of 1910 approach from the Lick Observatory Records Digital Archive
• HDR Astrophotography: Simulations Atlas of Past Comets (Antiquity to 1699) by Nicolas Lefaudeux
• HDR Astrophotography: Simulations Atlas of Past Comets (1900 to 1999) by Nicolas Lefaudeux

References

1. Delehanty, Marc. "Comets, awesome celestial objects". AstronomyToday. Archived from the original on 4 September 2011. Retrieved 15 March 2007. https://web.archive.org/web/20110904031752/http://www.astronomytoday.com/astronomy/comets.html ↩

2. Brady, Joseph L. (1982). "Halley's Comet AD 1986 to 2647 BC". Journal of the British Astronomical Association. 92. Lawrence Livermore Laboratory, University of California: 209. Bibcode:1982JBAA...92..209B. /wiki/Bibcode_(identifier) ↩

3. "Halley". Merriam–Webster Online. Retrieved 21 December 2009. http://www.merriam-webster.com/dictionary/Halley ↩

4. Ridpath, Ian (1985). "Saying Hallo to Halley". Revised extracts from "A Comet Called Halley" by Ian Ridpath, published by Cambridge University Press in 1985. Retrieved 8 May 2015. /wiki/Ian_Ridpath ↩

5. That is, with the vowel of hall and in some accents homophonous with holly. ↩

6. "New York Times Science Q&A". The New York Times. 14 May 1985. Retrieved 9 January 2011. https://www.nytimes.com/1985/05/14/science/q-a-237647.html ↩

7. Lancaster-Brown 1985, pp. 14, 25. - Lancaster-Brown, Peter (1985). Halley & His Comet. Blandford Press. ISBN 0-7137-1447-6. https://archive.org/details/halleyhiscomet00pete ↩

8. Lancaster-Brown 1985, p. 35. - Lancaster-Brown, Peter (1985). Halley & His Comet. Blandford Press. ISBN 0-7137-1447-6. https://archive.org/details/halleyhiscomet00pete ↩

9. D. W. Hughes (1988). "The 'Principia' and Comets". Notes and Records of the Royal Society of London. 42 (1): 53–74. doi:10.1098/rsnr.1988.0007. JSTOR 531369. https://www.jstor.org/stable/531369 ↩

10. Lancaster-Brown 1985, p. 76. - Lancaster-Brown, Peter (1985). Halley & His Comet. Blandford Press. ISBN 0-7137-1447-6. https://archive.org/details/halleyhiscomet00pete ↩

11. Lancaster-Brown 1985, p. 76. - Lancaster-Brown, Peter (1985). Halley & His Comet. Blandford Press. ISBN 0-7137-1447-6. https://archive.org/details/halleyhiscomet00pete ↩

12. Brady, Joseph L. (1982). "Halley's Comet AD 1986 to 2647 BC". Journal of the British Astronomical Association. 92. Lawrence Livermore Laboratory, University of California: 209. Bibcode:1982JBAA...92..209B. /wiki/Bibcode_(identifier) ↩

13. Lancaster-Brown 1985, p. 78. - Lancaster-Brown, Peter (1985). Halley & His Comet. Blandford Press. ISBN 0-7137-1447-6. https://archive.org/details/halleyhiscomet00pete ↩

14. Yeomans, Donald Keith; Rahe, Jürgen; Freitag, Ruth S. (1986). "The History of Comet Halley". Journal of the Royal Astronomical Society of Canada. 80: 81. Bibcode:1986JRASC..80...62Y. /wiki/Bibcode_(identifier) ↩

15. Lancaster-Brown 1985, p. 88. - Lancaster-Brown, Peter (1985). Halley & His Comet. Blandford Press. ISBN 0-7137-1447-6. https://archive.org/details/halleyhiscomet00pete ↩

16. Greene, John C. (1954). "Some Aspects of American Astronomy 1750-1815". Isis. 45 (4): 339–358. doi:10.1086/348356. ISSN 0021-1753. JSTOR 226781. https://www.jstor.org/stable/226781 ↩

17. "Black Genius: Science, Race, and the Extraordinary Portrait of Francis Williams - Talk at V&A South Kensington · V&A". Victoria and Albert Museum. Retrieved 17 October 2024. https://www.vam.ac.uk/event/BE4J645Oz3X/black-genius-the-extraordinary-portrait-of-francis-williams ↩

18. Dabhoiwala, Fara (11 November 2024). "A Man of Parts and Learning". London Review of Books. Vol. 46, no. 22. ISSN 0260-9592. Retrieved 6 December 2024. https://www.lrb.co.uk/the-paper/v46/n22/fara-dabhoiwala/a-man-of-parts-and-learning ↩

19. Ferguson, Donna (16 October 2024). "X-ray evidence of Black maths scholar portrait reveals snubbed genius". The Guardian. ISSN 0261-3077. Retrieved 17 October 2024. https://www.theguardian.com/artanddesign/2024/oct/16/x-ray-evidence-black-maths-scholar-portrait-francis-williams-uncovers-genius ↩

20. Dabhoiwala, Fara (11 November 2024). "A Man of Parts and Learning". London Review of Books. Vol. 46, no. 22. ISSN 0260-9592. Retrieved 6 December 2024. https://www.lrb.co.uk/the-paper/v46/n22/fara-dabhoiwala/a-man-of-parts-and-learning ↩

21. Dabhoiwala, Fara (11 November 2024). "A Man of Parts and Learning". London Review of Books. Vol. 46, no. 22. ISSN 0260-9592. Retrieved 6 December 2024. https://www.lrb.co.uk/the-paper/v46/n22/fara-dabhoiwala/a-man-of-parts-and-learning ↩

22. Lancaster-Brown 1985, p. 86. - Lancaster-Brown, Peter (1985). Halley & His Comet. Blandford Press. ISBN 0-7137-1447-6. https://archive.org/details/halleyhiscomet00pete ↩

23. Sagan & Druyan 1985, p. 74. - Sagan, Carl; Druyan, Ann (1985). Comet. Random House. ISBN 0-394-54908-2. https://archive.org/details/comet00saga ↩

24. Lancaster-Brown 1985, pp. 84–85. - Lancaster-Brown, Peter (1985). Halley & His Comet. Blandford Press. ISBN 0-7137-1447-6. https://archive.org/details/halleyhiscomet00pete ↩

25. Hughes, David W.; Fowler, P. H.; Lovell, B.; Lynden-Bell, D.; et al. (September 1987). "The History of Halley's Comet [and Discussion]". Philosophical Transactions of the Royal Society A. 323 (1572): 349–367. Bibcode:1987RSPTA.323..349H. doi:10.1098/rsta.1987.0091. JSTOR 37959. S2CID 123592786. /wiki/Philosophical_Transactions_of_the_Royal_Society_A ↩

26. Hughes, David W.; Fowler, P. H.; Lovell, B.; Lynden-Bell, D.; et al. (September 1987). "The History of Halley's Comet [and Discussion]". Philosophical Transactions of the Royal Society A. 323 (1572): 349–367. Bibcode:1987RSPTA.323..349H. doi:10.1098/rsta.1987.0091. JSTOR 37959. S2CID 123592786. /wiki/Philosophical_Transactions_of_the_Royal_Society_A ↩

27. Hughes, David W.; Fowler, P. H.; Lovell, B.; Lynden-Bell, D.; et al. (September 1987). "The History of Halley's Comet [and Discussion]". Philosophical Transactions of the Royal Society A. 323 (1572): 349–367. Bibcode:1987RSPTA.323..349H. doi:10.1098/rsta.1987.0091. JSTOR 37959. S2CID 123592786. /wiki/Philosophical_Transactions_of_the_Royal_Society_A ↩

28. Brodetsky, Selig. "Astronomy in the Babylonian Talmud". Jewish Review. 1911: 60. /wiki/Selig_Brodetsky ↩

29. "Tractate Horioth chapter 3". https://www.jewishvirtuallibrary.org/tractate-horioth-chapter-3 ↩

30. Rayner 1998, pp. 108–111. - Rayner, John D. (1998). A Jewish Understanding of the World. Berghahn Books. pp. 108–111. ISBN 1-57181-973-8. ↩

31. Veron, Phillipe (1982). "La comète de Halley et Mira Ceti dans le Talmud?". L'Astronomie. 96: 351–355. Bibcode:1982LAstr..96..351V. /wiki/Philippe_V%C3%A9ron ↩

32. Stephenson, F. Richard; Yau, Kevin K. C., "Oriental tales of Halley's Comet", New Scientist, vol. 103, no. 1423, pp. 30–32, 27 September 1984 ISSN 0262-4079 /wiki/F._Richard_Stephenson ↩

33. Yeomans, Donald Keith; Rahe, Jürgen; Freitag, Ruth S. (1986). "The History of Comet Halley". Journal of the Royal Astronomical Society of Canada. 80: 70. Bibcode:1986JRASC..80...62Y. Figure 4. The minimum and maximum intervals are 74.42 years (1835-1910) and 79.25 years (451-530). /wiki/Bibcode_(identifier) ↩

34. T. Hromakina, I. Belskaya, Yu. Krugly, V. Rumyantsev, O. Golubov, I. Kyrylenko, O. Ivanova. S. Velichko, I. Izvekova, A. Sergeyev, I. Slyusarev and I. Molotov (March 2021). "Small Solar System objects on highly inclined orbits". Astronomy and Astrophysics. 647 (A71): A71. arXiv:2101.04541. doi:10.1051/0004-6361/202039737.{{cite journal}}: CS1 maint: multiple names: authors list (link) /wiki/ArXiv_(identifier) ↩

35. Russell, C. T. (June 1988). "The interaction of the solar wind with Comet Halley – Upwind and downwind". Quarterly Journal of the Royal Astronomical Society. 29: 157–173. Bibcode:1988QJRAS..29..157R. https://articles.adsabs.harvard.edu//full/1988QJRAS..29..157R/0000160.000.html ↩

36. "Chapter 5: Planetary Orbits". NASA. 20 July 2023. Retrieved 31 August 2024. https://science.nasa.gov/learn/basics-of-space-flight/chapter5-1/ ↩

37. "1P/Halley Orbit". Minor Planet Center. Archived from the original on 4 July 2022. Retrieved 28 June 2022. (epoch 451 is 79.29 years) https://www.minorplanetcenter.net/db_search/show_object?object_id=1P ↩

38. "JPL Small-Body Database Browser: 1P/Halley" (11 January 1994 last obs). Jet Propulsion Laboratory. Archived from the original on 27 April 2015. Retrieved 28 June 2022. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1P&view=OPC ↩

39. "Meteor Streams". Jet Propulsion Laboratory. Retrieved 15 March 2007. https://ssd.jpl.nasa.gov/?meteor_streams ↩

40. Morbidelli, Alessandro (2005). "Origin and dynamical evolution of comets and their reservoirs". arXiv:astro-ph/0512256. /wiki/ArXiv_(identifier) ↩

41. Hughes, David W.; Fowler, P. H.; Lovell, B.; Lynden-Bell, D.; et al. (September 1987). "The History of Halley's Comet [and Discussion]". Philosophical Transactions of the Royal Society A. 323 (1572): 349–367. Bibcode:1987RSPTA.323..349H. doi:10.1098/rsta.1987.0091. JSTOR 37959. S2CID 123592786. /wiki/Philosophical_Transactions_of_the_Royal_Society_A ↩

42. Morbidelli, Alessandro (2005). "Origin and dynamical evolution of comets and their reservoirs". arXiv:astro-ph/0512256. /wiki/ArXiv_(identifier) ↩

43. Morbidelli, Alessandro (2005). "Origin and dynamical evolution of comets and their reservoirs". arXiv:astro-ph/0512256. /wiki/ArXiv_(identifier) ↩

44. Jewitt, David C. (2002). "From Kuiper Belt Object to Cometary Nucleus: The Missing Ultrared Matter". The Astronomical Journal. 123 (2): 1039–1049. Bibcode:2002AJ....123.1039J. doi:10.1086/338692. S2CID 122240711. /wiki/David_C._Jewitt ↩

45. "Small Body Database Query". NASA. Retrieved 15 July 2024. https://ssd.jpl.nasa.gov/tools/sbdb_query.html#!#results ↩

46. Fernández, Yanga R. (28 July 2015). "List of Jupiter-Family and Halley-Family Comets". University of Central Florida: Physics. Retrieved 6 September 2015. /wiki/Yanga_R._Fern%C3%A1ndez ↩

47. Morbidelli, Alessandro (2005). "Origin and dynamical evolution of comets and their reservoirs". arXiv:astro-ph/0512256. /wiki/ArXiv_(identifier) ↩

48. Jewitt, David C. (2002). "From Kuiper Belt Object to Cometary Nucleus: The Missing Ultrared Matter". The Astronomical Journal. 123 (2): 1039–1049. Bibcode:2002AJ....123.1039J. doi:10.1086/338692. S2CID 122240711. /wiki/David_C._Jewitt ↩

49. Jewitt, David C. (2002). "From Kuiper Belt Object to Cometary Nucleus: The Missing Ultrared Matter". The Astronomical Journal. 123 (2): 1039–1049. Bibcode:2002AJ....123.1039J. doi:10.1086/338692. S2CID 122240711. /wiki/David_C._Jewitt ↩

50. Gladman, Brett J.; et al. (2009). "Discovery of the first retrograde transneptunian object". The Astrophysical Journal. 697 (2): L91 – L94. Bibcode:2009ApJ...697L..91G. doi:10.1088/0004-637X/697/2/L91. /wiki/Brett_J._Gladman ↩

51. Olsson-Steel, Duncan I. (1987). "The dynamical lifetime of comet P/Halley". Astronomy and Astrophysics. 187 (1–2): 909–912. Bibcode:1987A&A...187..909O. /wiki/Bibcode_(identifier) ↩

52. Olsson-Steel, Duncan I. (1987). "The dynamical lifetime of comet P/Halley". Astronomy and Astrophysics. 187 (1–2): 909–912. Bibcode:1987A&A...187..909O. /wiki/Bibcode_(identifier) ↩

53. Yeomans 1991, pp. 260–261. - Yeomans, Donald Keith (1991). Comets: A Chronological History of Observation, Science, Myth, and Folklore. Wiley and Sons. pp. 260–261. ISBN 0-471-61011-9. https://archive.org/details/cometschronologi0000yeom ↩

54. Chirikov, Boris V.; Vecheslavov, Vitold V. (1989). "Chaotic dynamics of comet Halley" (PDF). Astronomy and Astrophysics. 221 (1): 146–154. Bibcode:1989A&A...221..146C. /wiki/Boris_Chirikov ↩

55. Chirikov, R. V.; Vecheslavov, V. V. (August 1989). "Chaotic dynamics of Comet Halley". Astronomy and Astrophysics. 221 (1): 146–154. Bibcode:1989A&A...221..146C. /wiki/Bibcode_(identifier) ↩

56. Chirikov, R. V.; Vecheslavov, V. V. (August 1989). "Chaotic dynamics of Comet Halley". Astronomy and Astrophysics. 221 (1): 146–154. Bibcode:1989A&A...221..146C. /wiki/Bibcode_(identifier) ↩

57. Lages, José; Shepelyansky, Dima L.; Shevchenko, Ivan I. (2018). "Kepler map". Scholarpedia. 13 (2): 33238. Bibcode:2018SchpJ..1333238L. doi:10.4249/scholarpedia.33238. https://doi.org/10.4249%2Fscholarpedia.33238 ↩

58. Hughes, D. W. (March 1985). "The size, mass, mass loss and age of Halley's comet". Monthly Notices of the Royal Astronomical Society. 213 (1): 103–109. Bibcode:1985MNRAS.213..103H. doi:10.1093/mnras/213.1.103. https://doi.org/10.1093%2Fmnras%2F213.1.103 ↩

59. Williams, Matt (12 June 2015). "What Is Halley's Comet?". Universe today. http://www.universetoday.com/48991/halleys-comet/ ↩

60. Jewitt, David C. (2002). "From Kuiper Belt Object to Cometary Nucleus: The Missing Ultrared Matter". The Astronomical Journal. 123 (2): 1039–1049. Bibcode:2002AJ....123.1039J. doi:10.1086/338692. S2CID 122240711. /wiki/David_C._Jewitt ↩

61. Delehanty, Marc. "Comets, awesome celestial objects". AstronomyToday. Archived from the original on 4 September 2011. Retrieved 15 March 2007. https://web.archive.org/web/20110904031752/http://www.astronomytoday.com/astronomy/comets.html ↩

62. Brandt, John C. (February 2018). "Halley's Comet". AccessScience. McGraw Hill. doi:10.1036/1097-8542.305800. /wiki/Doi_(identifier) ↩

63. Altwegg, K.; Balsiger, H.; Geiss, J.; Goldstein, R.; Ip, W.-H.; Meier, A. (1993). "The ion population between 1300 km and 230000 km in the coma of comet P/Halley". Astronomy and Astrophysics. 279 (1): 260–266. Bibcode:1993A&A...279..260A. /wiki/Bibcode_(identifier) ↩

64. Delehanty, Marc. "Comets, awesome celestial objects". AstronomyToday. Archived from the original on 4 September 2011. Retrieved 15 March 2007. https://web.archive.org/web/20110904031752/http://www.astronomytoday.com/astronomy/comets.html ↩

65. Delehanty, Marc. "Comets, awesome celestial objects". AstronomyToday. Archived from the original on 4 September 2011. Retrieved 15 March 2007. https://web.archive.org/web/20110904031752/http://www.astronomytoday.com/astronomy/comets.html ↩

66. Brandt, John C. (February 2018). "Halley's Comet". AccessScience. McGraw Hill. doi:10.1036/1097-8542.305800. /wiki/Doi_(identifier) ↩

67. Biermann, Ludwig F.; Lüst, Rhea (October 1958). "The Tails of Comets". Scientific American. 199 (4): 44–51. Bibcode:1958SciAm.199d..44B. doi:10.1038/scientificamerican1058-44. JSTOR 24944791. /wiki/Bibcode_(identifier) ↩

68. Brandt, J. C.; Niedner, M. B. (1986). Plasma structures in comets P/Halley and Giacobini-Zinner. Exploration of Halley’s Comet. Astronomy and Astrophysics. Vol. 187. pp. 281–286. doi:10.1007/978-3-642-82971-0_50. ISBN 978-3-642-82971-0. 978-3-642-82971-0 ↩

69. Keller, H. U.; Delamere, W. A.; Huebner, W. F.; Reitsema, H. J.; Schmidt, H. U.; Whipple, F. L.; Wilhelm, K.; Curdt, W.; Kramm, R.; Thomas, N.; Arpigny, C.; Barbieri, C.; Bonnet, R. M.; Cazes, S.; Coradini, M.; Cosmovici, C. B.; Hughes, D. W.; Jamar, C.; Malaise, D.; Schmidt, K.; Schmidt, W. K. H.; Seige, P. (1988). Comet P/Halley's nucleus and its activity. Exploration of Halley’s Comet. Astronomy and Astrophysics. Vol. 187, no. 1–2. pp. 807–823. Bibcode:1987A&A...187..807K. doi:10.1007/978-3-642-82971-0_138. ISBN 978-3-642-82973-4. 978-3-642-82973-4 ↩

70. Reitsema, H. J.; Delamere, W. A.; Huebner, W. F.; Keller, H. U.; Schmidt, H. U.; Schmidt, W. K. H.; Whipple, F. L.; Wilhelm, K. (1986). "ESA SP-250". In ESA, Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet. 2: 351. ↩

71. Lamy, Philippe L.; Toth, Imre; Fernández, Yanga R.; Weaver, Harold A. (2004). "The Sizes, Shapes, Albedos, and Colors of Cometary Nuclei". In Festou, M.; Keller, H. U.; Weaver, Harold A. (eds.). Comets II. University of Arizona Press. pp. 223–264. Bibcode:2004come.book..223L. ISBN 978-0-8165-2450-1. 978-0-8165-2450-1 ↩

72. Reitsema, H. J.; Delamere, W. A.; Huebner, W. F.; Keller, H. U.; Schmidt, H. U.; Schmidt, W. K. H.; Whipple, F. L.; Wilhelm, K. (1986). "ESA SP-250". In ESA, Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet. 2: 351. ↩

73. Mendis, D. A. (1986). Battrick, B.; Rolfe, E. J.; Reinhard, R. (ed.). "Exploration of Halley's Comet: Symposium Summary". The Exploration of Halley's Comet. 2. Dust and Nucleus Proceedings of the 20th ESLAB Symposium held in Heidelberg, West Germany, 27-31 Oct. 1986: European Space Agency: 441. Bibcode:1986ESASP.250b.441M.{{cite journal}}: CS1 maint: location (link) CS1 maint: multiple names: editors list (link) https://adsabs.harvard.edu/full/1986ESASP.250b.441M ↩

74. Rickman, H. (1989). "The nucleus of comet Halley: Surface structure, mean density, gas and dust production". Advances in Space Research. 9 (3): 59–71. Bibcode:1989AdSpR...9c..59R. doi:10.1016/0273-1177(89)90241-X. https://www.sciencedirect.com/science/article/abs/pii/027311778990241X ↩

75. Keller, Horst Uwe; Britt, Daniel; Buratti, Bonnie J.; Thomas, Nicolas (2005). "In Situ Observations of Cometary Nuclei". In Festou, Michel; Keller, Horst Uwe; Weaver, Harold A. (eds.). Comets II. University of Arizona Press. pp. 211–222. ISBN 978-0-8165-2450-1. Archived (PDF) from the original on 1 July 2024. 978-0-8165-2450-1 ↩

76. Sagdeev, Roald Z.; Elyasberg, Pavel E.; Moroz, Vasily I. (1988). "Is the nucleus of Comet Halley a low density body?". Nature. 331 (6153): 240–242. Bibcode:1988Natur.331..240S. doi:10.1038/331240a0. S2CID 4335780. /wiki/Pavel_Elyasberg ↩

77. Keller, Horst Uwe; Britt, Daniel; Buratti, Bonnie J.; Thomas, Nicolas (2005). "In Situ Observations of Cometary Nuclei". In Festou, Michel; Keller, Horst Uwe; Weaver, Harold A. (eds.). Comets II. University of Arizona Press. pp. 211–222. ISBN 978-0-8165-2450-1. Archived (PDF) from the original on 1 July 2024. 978-0-8165-2450-1 ↩

78. Brice Hoover, Richard (November 2004). "Astrobiology of comets". In Hoover, Richard B.; Levin, Gilbert V.; Rozanov, Alexei Y. (eds.). Instruments, Methods, and Missions for Astrobiology VIII. Proceedings of SPIE. Vol. 5555. pp. 93–106. doi:10.1117/12.566496 – via ResearchGate. https://www.researchgate.net/publication/260077113 ↩

79. Brandt, John C. (February 2018). "Halley's Comet". AccessScience. McGraw Hill. doi:10.1036/1097-8542.305800. /wiki/Doi_(identifier) ↩

80. Keller, Horst Uwe; Britt, Daniel; Buratti, Bonnie J.; Thomas, Nicolas (2005). "In Situ Observations of Cometary Nuclei". In Festou, Michel; Keller, Horst Uwe; Weaver, Harold A. (eds.). Comets II. University of Arizona Press. pp. 211–222. ISBN 978-0-8165-2450-1. Archived (PDF) from the original on 1 July 2024. 978-0-8165-2450-1 ↩

81. Keller, Horst Uwe; Britt, Daniel; Buratti, Bonnie J.; Thomas, Nicolas (2005). "In Situ Observations of Cometary Nuclei". In Festou, Michel; Keller, Horst Uwe; Weaver, Harold A. (eds.). Comets II. University of Arizona Press. pp. 211–222. ISBN 978-0-8165-2450-1. Archived (PDF) from the original on 1 July 2024. 978-0-8165-2450-1 ↩

82. Woods, Thomas N.; Feldman, Paul D.; Dymond, Kenneth F.; Sahnow, David J. (1986). "Rocket ultraviolet spectroscopy of comet Halley and abundance of carbon monoxide and carbon". Nature. 324 (6096): 436–438. Bibcode:1986Natur.324..436W. doi:10.1038/324436a0. S2CID 4333809. /wiki/Bibcode_(identifier) ↩

83. Chyba, Christopher F.; Sagan, Carl (1987). "Infrared emission by organic grains in the coma of comet Halley". Nature. 330 (6146): 350–353. Bibcode:1987Natur.330..350C. doi:10.1038/330350a0. S2CID 4351413. /wiki/Christopher_Chyba ↩

84. "Giotto:Halley". European Space Agency. 2006. Retrieved 5 December 2009. http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=31878 ↩

85. Brandt, John C. (February 2018). "Halley's Comet". AccessScience. McGraw Hill. doi:10.1036/1097-8542.305800. /wiki/Doi_(identifier) ↩

86. Mendis, D. Asoka (1988). "A Postencounter view of comets". Annual Review of Astronomy and Astrophysics. 26 (1): 11–49. Bibcode:1988ARA&A..26...11M. doi:10.1146/annurev.aa.26.090188.000303. /wiki/Bibcode_(identifier) ↩

87. Brandt, John C. (February 2018). "Halley's Comet". AccessScience. McGraw Hill. doi:10.1036/1097-8542.305800. /wiki/Doi_(identifier) ↩

88. Brandt, John C. (February 2018). "Halley's Comet". AccessScience. McGraw Hill. doi:10.1036/1097-8542.305800. /wiki/Doi_(identifier) ↩

89. Weaver, Harold A.; et al. (1997). "The Activity and Size of the Nucleus of Comet Hale–Bopp (C/1995 O1)". Science. 275 (5308): 1900–1904. Bibcode:1997Sci...275.1900W. doi:10.1126/science.275.5308.1900. PMID 9072959. S2CID 25489175. /wiki/Bibcode_(identifier) ↩

90. Michael J. S. Belton; Harvey Butcher (1982). "Limits on the nucleus of Halley's Comet". Nature. 298 (5871): 249–251. Bibcode:1982Natur.298..249B. doi:10.1038/298249a0. Retrieved 14 July 2024. https://www.nature.com/articles/298249a0 ↩

91. Mendis, D. Asoka (1988). "A Postencounter view of comets". Annual Review of Astronomy and Astrophysics. 26 (1): 11–49. Bibcode:1988ARA&A..26...11M. doi:10.1146/annurev.aa.26.090188.000303. /wiki/Bibcode_(identifier) ↩

92. Keller, Horst Uwe; Britt, Daniel; Buratti, Bonnie J.; Thomas, Nicolas (2005). "In Situ Observations of Cometary Nuclei". In Festou, Michel; Keller, Horst Uwe; Weaver, Harold A. (eds.). Comets II. University of Arizona Press. pp. 211–222. ISBN 978-0-8165-2450-1. Archived (PDF) from the original on 1 July 2024. 978-0-8165-2450-1 ↩

93. "Voyages to Comets". NASA. 2005. Retrieved 5 December 2009. https://www.nasa.gov/exploration/whyweexplore/Why_We_17.html ↩

94. Hughes, David W.; Fowler, P. H.; Lovell, B.; Lynden-Bell, D.; et al. (September 1987). "The History of Halley's Comet [and Discussion]". Philosophical Transactions of the Royal Society A. 323 (1572): 349–367. Bibcode:1987RSPTA.323..349H. doi:10.1098/rsta.1987.0091. JSTOR 37959. S2CID 123592786. /wiki/Philosophical_Transactions_of_the_Royal_Society_A ↩

95. Kronk 1999, p. 6. - Kronk, Gary W. (1999). Cometography, vol. 1: Ancient-1799. Cambridge University Press. ISBN 978-0-521-58504-0. https://books.google.com/books?id=Umxbb68tmZMC&pg=PA6 ↩

96. Stephenson, F. Richard; Yau, Kevin K. C.; Hunger, Hermann (18 April 1985). "Records of Halley's Comet on Babylonian tablets". Nature. 314 (6012): 587–592. Bibcode:1985Natur.314..587S. doi:10.1038/314587a0. S2CID 33251962. /wiki/Hermann_Hunger ↩

97. Walker, C. B. F. (18 April 1985). "Archaeoastronomy: Halley's comet in Babylonia". Nature. 314 (6012): 576–577. Bibcode:1985Natur.314..576W. doi:10.1038/314576b0. /wiki/Nature_(journal) ↩

98. Stephenson, F. Richard; Yau, Kevin K. C.; Hunger, Hermann (18 April 1985). "Records of Halley's Comet on Babylonian tablets". Nature. 314 (6012): 587–592. Bibcode:1985Natur.314..587S. doi:10.1038/314587a0. S2CID 33251962. /wiki/Hermann_Hunger ↩

99. Gurzadyan, Vahe G.; Vardanyan, Ruben (4 August 2004). "Halley's Comet of 87 BC on the coins of Armenian king Tigranes?". Astronomy & Geophysics. 45 (4): 4.06. arXiv:physics/0405073. Bibcode:2004A&G....45d...6G. doi:10.1046/j.1468-4004.2003.45406.x. S2CID 119357985. /wiki/Vahe_Gurzadyan ↩

100. Kronk, Gary W. "1P/Halley". cometography.com. Archived from the original on 23 November 2017. Retrieved 13 October 2008. /wiki/Gary_W._Kronk ↩

101. Yeomans, Donald Keith (1998). "Great Comets in History". Jet Propulsion Laboratory. Retrieved 15 March 2007. https://ssd.jpl.nasa.gov/?great_comets ↩

102. Chambers, George F. (1909). The Story of the Comets. The Clarenden Press. p. 123. https://archive.org/details/b31349596 ↩

103. Humphreys, Colin (1995). "The Star of Bethlehem". Science and Christian Belief. 5: 83–101. /wiki/Colin_Humphreys ↩

104. "Horayot 10a:19". www.sefaria.org. Retrieved 14 February 2022. https://www.sefaria.org/Horayot.10a.19 ↩

105. Ne'eman, Yuval (1983). "Astronomy in Israel: From Og's Circle to the Wise Observatory". Tel-Aviv University. Retrieved 15 March 2007. /wiki/Yuval_Ne%27eman ↩

106. Jaroff, Leon (16 December 1985). "Science: Historic Cometary Tales". Time Magazine. Retrieved 29 June 2024. /wiki/Leon_Jaroff ↩

107. William Whiston: "Whether Josephus means that this star was different from that comet which lasted a whole year, I cannot certainly determine. His words most favour their being different one from another." /wiki/William_Whiston ↩

108. "Flavius Josephus, The Wars of the Jews, Book VI, section 288". www.perseus.tufts.edu. Retrieved 30 June 2024. https://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.01.0148:book=6:section=288 ↩

109. Horowitz, Wayne (1996). "Halley's Comet and Judaean Revolts Revisited". Catholic Biblical Quarterly. 58 (3): 456–459. ISSN 0008-7912. JSTOR 43722716. /wiki/Wayne_Horowitz ↩

110. Ravené, Gustave (9 March 1897). "The Appearance of Halley's Comet in A.D. 141". The Observatory. 20. Milan: 203–205. Bibcode:1897Obs....20..203R. Retrieved 8 October 2024. The comet observed by the Chinese in A.D. 141 is in fact Halley's Comet https://adsabs.harvard.edu/full/1897Obs....20..203R ↩

111. Aiyar, K. G. Sesha (1937). "Yanaik-kat-Sey Mantaran-Ceral". Chera Kings of the Sangam Period. London: Luzac and Co. pp. 63–66. https://archive.org/details/in.ernet.dli.2015.277483 ↩

112. Yeomans, Donald Keith (1998). "Great Comets in History". Jet Propulsion Laboratory. Retrieved 15 March 2007. https://ssd.jpl.nasa.gov/?great_comets ↩

113. Schultheis, Evan Michael (2019). "5". The Battle of the Catalaunian Fields, 451 AD: Flavius Aetius, Attila the Hun, and the Transformation of Gaul. Pen & Sword Military. p. 70. ISBN 9781526745651. 9781526745651 ↩

114. Kronk, Gary W. (2009). Cometography: A Catalog of Comets. 1933-1959. Vol. 4. Cambridge University Press. pp. 81–82. ISBN 978-0-521-58504-0. 978-0-521-58504-0 ↩

115. Olson, Roberta J.; Pasachoff, Jay M. (1986). "New information on Comet Halley as depicted by Giotto di Bondone and other Western artists". In ESA, Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet. 3: 201–213. Bibcode:1986ESASP.250c.201O. /wiki/Roberta_Olson ↩

116. Neuhäuser, D.L.; Neuhäuser, R.; Mugrauer, M.; Harrak, A.; Chapman, J. (August 2021). "Orbit determination just from historical observations? Test case: The comet of AD 760 is identified as 1P/Halley". Icarus. 364: 114278. arXiv:2107.07241. Bibcode:2021Icar..36414278N. doi:10.1016/j.icarus.2020.114278. /wiki/ArXiv_(identifier) ↩

117. "Horizons Batch for 1P/Halley (90000015) on 837AD-Apr-10" (Earth approach occurs when deldot flips from negative to positive @ 837-Apr-10 12:13). JPL Horizons. Archived from the original on 30 June 2022. Retrieved 29 June 2022. (SAO/837) https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000015%27&START_TIME=%27837AD-Apr-10%2012:00%27&STOP_TIME=%27837AD-Apr-10%2012:30%27&STEP_SIZE=%271%20minutes%27&QUANTITIES=%2719,20,23%27 ↩

118. Yeomans, Donald Keith (1998). "Great Comets in History". Jet Propulsion Laboratory. Retrieved 15 March 2007. https://ssd.jpl.nasa.gov/?great_comets ↩

119. Kronk, Gary W. "1P/Halley". cometography.com. Archived from the original on 23 November 2017. Retrieved 13 October 2008. /wiki/Gary_W._Kronk ↩

120. Son of Charlemagne: A Contemporary Life of Louis the Pious. Translated by Cabaniss, Allen. Syracuse: Syracuse University Press. 1961. p. 113. /wiki/Vita_Hludovici ↩

121. "The Annals of Ulster AD 431–1201". Corpus of Electronic Texts. University College Cork. Retrieved 25 March 2024. https://celt.ucc.ie/published/T100001A/index.html ↩

122. Yeomans, Donald Keith (1998). "Great Comets in History". Jet Propulsion Laboratory. Retrieved 15 March 2007. https://ssd.jpl.nasa.gov/?great_comets ↩

123. William of Malmesbury; Gesta regum Anglorum / The history of the English Kings, edited and translated by Mynors, R. A. B.; Thomson, R. M.; and Winterbottom, M.; 2 vols., Oxford Medieval Texts (1998–99), p. 121 ↩

124. "The Annals of the Four Masters". Corpus of Electronic Texts. University College Cork. Retrieved 25 March 2024. https://celt.ucc.ie/published/T100005B/index.html ↩

125. Brazil, Ben (18 September 2005). "Chaco Canyon mystery tour". The LA Times. Archived from the original on 9 January 2021. Retrieved 11 November 2021. https://www.latimes.com/archives/la-xpm-2005-sep-18-tr-chaco18-story.html ↩

126. Lupus Protospatarius Barensis, Rerum in Regno Neapolitano Gestarum Breve Chronicon ab Anno Sal. 860 vsque ad 1102 (in Latin), The Latin Library, Anno 1067. mense Maii mortuus est Constantinus Ducas Imp. et Michael filius eius suscepit Imperium, et apparuit stella cometa, et Comes Normanniae Robertus fecit bellum cum Arnaldo Rege Anglorum, et vicit Robertus, qui et factus est Rex super gentem Anglorum. /wiki/Lupus_Protospatharius ↩

127. Olson, Roberta J. M. (1979). "Giotto's portrait of Halley's Comet". Scientific American. 240 (5): 160–171. Bibcode:1979SciAm.240e.160O. doi:10.1038/scientificamerican0579-160. JSTOR 24965203. /wiki/Roberta_Olson ↩

128. Johnson, George (28 March 1997). "Comets Breed Fear, Fascination and Web Sites". The New York Times. Retrieved 27 September 2009. https://www.nytimes.com/1997/03/28/us/comets-breed-fear-fascination-and-web-sites.html ↩

129. Cook, David (15 April 2008). "Apocalyptic Incidents during the Mongol Invasions". In Brandes, Wolfram; Schmieder, Felicitas (eds.). Endzeiten: Eschatologie in den monotheistischen Weltreligionen. Millennium-Studien / Millennium Studies. De Gruyter. pp. 293–312. doi:10.1515/9783110209709.293. ISBN 9783110186215. 9783110186215 ↩

130. Choi, Go-Eun; Lee, Ki-Won; Mihn, Byeong-Hee; Ahn, Young Sook (2017). "Daytime Visibility of Halley's Comet in 1222". The Bulletin of the Korean Astronomical Society. 42 (2). The Korean Astronomical Society: 70–71. Retrieved 6 July 2024. https://koreascience.kr/article/CFKO201723863198694.page ↩

131. There are doubts about the latter date. It is generally accepted that the comet was visible from about mid September until about early November. ↩

132. Olson, Roberta J.; Pasachoff, Jay M. (1986). "New information on Comet Halley as depicted by Giotto di Bondone and other Western artists". In ESA, Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet. 3: 201–213. Bibcode:1986ESASP.250c.201O. /wiki/Roberta_Olson ↩

133. Olson, Roberta J. M. (1979). "Giotto's portrait of Halley's Comet". Scientific American. 240 (5): 160–171. Bibcode:1979SciAm.240e.160O. doi:10.1038/scientificamerican0579-160. JSTOR 24965203. /wiki/Roberta_Olson ↩

134. Olson, Roberta J.; Pasachoff, Jay M. (1986). "New information on Comet Halley as depicted by Giotto di Bondone and other Western artists". In ESA, Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet. 3: 201–213. Bibcode:1986ESASP.250c.201O. /wiki/Roberta_Olson ↩

135. "New Names of Minor Planets" (PDF). WGSBN Bulletin. 2 (2): 9. 7 February 2022. Retrieved 5 July 2024. https://www.wgsbn-iau.org/files/Bulletins/V002/WGSBNBull_V002_002.pdf#page=9 ↩

136. Rerum Italicarum Scriptores, ed. Ludovico Antonio Muratori (Milan, 1730) v. 16 col. 770. ↩

137. Kronk 1999, pp. 253–255. - Kronk, Gary W. (1999). Cometography, vol. 1: Ancient-1799. Cambridge University Press. ISBN 978-0-521-58504-0. https://books.google.com/books?id=Umxbb68tmZMC&pg=PA6 ↩

138. Emerson, Edwin. Comet lore, Halley's comet in history and astronomy. New York, Printed by the Schilling press. p. 74. Retrieved 1 October 2017. https://archive.org/details/cometlorehalleys00emerrich/page/74 ↩

139. Botley, Cicely M. (1971). "The Legend of 1P/Halley 1456". The Observatory. 91: 125–126. Bibcode:1971Obs....91..125B. /wiki/Bibcode_(identifier) ↩

140. Slaje, Walter; inter alia, realia: "An Apparition of Halley's Comet in Kashmir observed by Śrīvara in AD 1456" in Steiner, Roland (ed.); Highland Philology: Results of a Text-Related Kashmir Panel at the 31st DOT, Marburg 2010, Studia Indologica Universitatis Halensis, 4, Halle 2012: 33–48 /wiki/Walter_Slaje ↩

141. The founding of Debre Berhan is described in the Ethiopian Royal Chronicles (Pankhurst, Richard; Oxford University Press, Addis Ababa, 1967, pp. 36–38). ↩

142. Kapoor, R.C. (10 July 2017). "Records of sighting of Halley's Comet in the 1531 apparition and an eclipse in Guru Nanak's references". Current Science. 113 (1): 173–179. JSTOR 26163925. /wiki/JSTOR_(identifier) ↩

143. Barker, Peter (2008). "Stoic alternatives to Aristotelian cosmology : Pena, Rothmann and Brahe, Summary". Revue d'histoire des sciences (in French). Tome 61 (2): 265–286. doi:10.3917/rhs.612.0265. ISSN 0151-4105. /wiki/Doi_(identifier) ↩

144. Grier 2005, pp. 11–25. - Grier, David Alan (2005). "The First Anticipated Return: Halley's Comet 1758". When Computers Were Human. Princeton: Princeton University Press. ISBN 0-691-09157-9. https://books.google.com/books?id=YTcDAQAAQBAJ&pg=PA11 ↩

145. Broughton, P. (1985). "The First Predicted Return of Comet Halley". Journal for the History of Astronomy. 16 (2): 123–132. Bibcode:1985JHA....16..123B. doi:10.1177/002182868501600203. S2CID 118670662. /wiki/Bibcode_(identifier) ↩

146. Broughton, P. (1985). "The First Predicted Return of Comet Halley". Journal for the History of Astronomy. 16 (2): 123–132. Bibcode:1985JHA....16..123B. doi:10.1177/002182868501600203. S2CID 118670662. /wiki/Bibcode_(identifier) ↩

147. Sagan & Druyan 1985, p. 57. - Sagan, Carl; Druyan, Ann (1985). Comet. Random House. ISBN 0-394-54908-2. https://archive.org/details/comet00saga ↩

148. Sagan & Druyan 1985, p. 57. - Sagan, Carl; Druyan, Ann (1985). Comet. Random House. ISBN 0-394-54908-2. https://archive.org/details/comet00saga ↩

149. Broughton, P. (1985). "The First Predicted Return of Comet Halley". Journal for the History of Astronomy. 16 (2): 123–132. Bibcode:1985JHA....16..123B. doi:10.1177/002182868501600203. S2CID 118670662. /wiki/Bibcode_(identifier) ↩

150. Abrahams, Peter (15 June 2009). "History of the Cauchoix objective". The history of the telescope & the binocular. Archived from the original on 17 November 2020. Retrieved 24 July 2020. https://web.archive.org/web/20201117191206/http://www.europa.com/~telscope/tsfrance.txt ↩

151. "Comet Halley in 1835". Smithsonian National Air and Space Museum. 9 June 2016. Retrieved 18 November 2019. https://airandspace.si.edu/multimedia-gallery/web12123-2011640jpg ↩

152. Sagan & Druyan 1985, p. 117. - Sagan, Carl; Druyan, Ann (1985). Comet. Random House. ISBN 0-394-54908-2. https://archive.org/details/comet00saga ↩

153. Todd, William G. (1910). "Saw Halley's Comet in 1835". Popular Astronomy. 18: 127. Bibcode:1910PA.....18..127T. /wiki/Bibcode_(identifier) ↩

154. Todd, William G. (1910). "Saw Halley's Comet in 1835". Popular Astronomy. 18: 127. Bibcode:1910PA.....18..127T. /wiki/Bibcode_(identifier) ↩

155. Lynn, W. T. (1909). "Halley's Comet in 1835". The Observatory. 32: 175–177. Bibcode:1909Obs....32..175L. /wiki/Bibcode_(identifier) ↩

156. Lynn, W. T. (1909). "Halley's Comet in 1835". The Observatory. 32: 175–177. Bibcode:1909Obs....32..175L. /wiki/Bibcode_(identifier) ↩

157. Lynn, W. T. (1909). "Halley's Comet in 1835". The Observatory. 32: 175–177. Bibcode:1909Obs....32..175L. /wiki/Bibcode_(identifier) ↩

158. Smith, J. A. (1986). "Halley's Comet: Canadian Observations and Reactions 1835–36 and 1910". Journal of the Royal Astronomical Society of Canada. 80 (1): 1–15. Bibcode:1986JRASC..80....1S. /wiki/Bibcode_(identifier) ↩

159. Smith, J. A. (1986). "Halley's Comet: Canadian Observations and Reactions 1835–36 and 1910". Journal of the Royal Astronomical Society of Canada. 80 (1): 1–15. Bibcode:1986JRASC..80....1S. /wiki/Bibcode_(identifier) ↩

160. Smith, J. A. (1986). "Halley's Comet: Canadian Observations and Reactions 1835–36 and 1910". Journal of the Royal Astronomical Society of Canada. 80 (1): 1–15. Bibcode:1986JRASC..80....1S. /wiki/Bibcode_(identifier) ↩

161. Smith, J. A. (1986). "Halley's Comet: Canadian Observations and Reactions 1835–36 and 1910". Journal of the Royal Astronomical Society of Canada. 80 (1): 1–15. Bibcode:1986JRASC..80....1S. /wiki/Bibcode_(identifier) ↩

162. "In Depth | 1P/Halley". NASA Solar System Exploration. 29 November 2017. Retrieved 7 November 2019. https://solarsystem.nasa.gov/asteroids-comets-and-meteors/comets/1p-halley/in-depth ↩

163. Lequeux 2015, p. 180. - Lequeux, James (2015). François Arago: A 19th Century French Humanist and Pioneer in Astrophysics. Springer. ISBN 978-3-319-20723-0. https://books.google.com/books?id=ikqGCgAAQBAJ&pg=PA180 ↩

164. Levasseur-Regourd, A. C. (2019), "From François Arago to small bodies exploration: Polarimetry as a tool to reveal properties of thin dust clouds in the Solar system and beyond" (PDF), EPSC-DPS Joint Meeting 2019, vol. 13 /wiki/Anny-Chantal_Levasseur-Regourd ↩

165. Yeomans, Donald Keith (1998). "Great Comets in History". Jet Propulsion Laboratory. Retrieved 15 March 2007. https://ssd.jpl.nasa.gov/?great_comets ↩

166. Yeomans, Donald Keith (1998). "Great Comets in History". Jet Propulsion Laboratory. Retrieved 15 March 2007. https://ssd.jpl.nasa.gov/?great_comets ↩

167. Mendis, D. Asoka (1988). "A Postencounter view of comets". Annual Review of Astronomy and Astrophysics. 26 (1): 11–49. Bibcode:1988ARA&A..26...11M. doi:10.1146/annurev.aa.26.090188.000303. /wiki/Bibcode_(identifier) ↩

168. Yeomans, Donald Keith (1998). "Great Comets in History". Jet Propulsion Laboratory. Retrieved 15 March 2007. https://ssd.jpl.nasa.gov/?great_comets ↩

169. Ridpath, Ian (1985). "Through the comet's tail". Revised extracts from "A Comet Called Halley" by Ian Ridpath, published by Cambridge University Press in 1985. Retrieved 19 June 2011. /wiki/Ian_Ridpath ↩

170. Nunnally, Brian (16 May 2011). "This Week in Science History: Halley's Comet". pfizer: ThinkScience Now. Archived from the original on 17 December 2012. Retrieved 19 June 2011. https://archive.today/20121217174930/https://science.pfizer.com/content/this-week-in-science-history-halleys-comet/ ↩

171. anonymous (8 February 1910). "Yerkes Observatory Finds Cyanogen in Spectrum of Halley's Comet". The New York Times. Retrieved 15 November 2009. https://www.nytimes.com/1910/02/08/archives/comets-poisonous-tail-yerkes-observatory-finds-cyanogen-in-spectrum.html ↩

172. Goodrich 2023, p. 83; Goodrich 2023, p. 238. - Goodrich, Richard J. (2023). Comet Madness. How the 1910 Return of Halley's Comet (Almost) Destroyed Civilization. Prometheus Books. p. 188. ISBN 9781633888579. https://books.google.com/books?id=B5ySEAAAQBAJ&pg=PA188 ↩

173. Strauss, Mark (November 2009). "Ten Notable Apocalypses That (Obviously) Didn't Happen". Smithsonian. Archived from the original on 6 August 2017. Retrieved 14 November 2009. /wiki/Mark_Strauss_(journalist) ↩

174. Strauss, Mark (November 2009). "Ten Notable Apocalypses That (Obviously) Didn't Happen". Smithsonian. Archived from the original on 6 August 2017. Retrieved 14 November 2009. /wiki/Mark_Strauss_(journalist) ↩

175. Goodrich 2023, p. 188. - Goodrich, Richard J. (2023). Comet Madness. How the 1910 Return of Halley's Comet (Almost) Destroyed Civilization. Prometheus Books. p. 188. ISBN 9781633888579. https://books.google.com/books?id=B5ySEAAAQBAJ&pg=PA188 ↩

176. Ting Chen; Lingfeng Lü (2022). "Astronomical or political: Interpretation of comets in times of crisis in Qing China". Journal for the History of Astronomy. 53 (1): 13–26. Bibcode:2022JHA....53...13C. doi:10.1177/00218286211070275. /wiki/Bibcode_(identifier) ↩

177. Hutson, James (1921). "Eclipses and Comets" . Chinese Life in the Tibetan Foothills . Shanghai: Far Eastern Geographical Establishment. p. 207. https://en.wikisource.org/wiki/Chinese_Life_in_the_Tibetan_Foothills/Book_8/Eclipses_and_Comets ↩

178. Rosenthal, Eric; Churchward, Hedley (1931). From Drury Lane to Mecca. Being an Account of the Strange Life and Adventures of Hedley Churchward (also Known as Mahmoud Mobarek Churchward), an English Convert to Islam. London: Sampson Low. /wiki/Hedley_Churchward ↩

179. anonymous, chromolithographie publicitaire au Bon Marché (titre forgé), Bibliothèque numérique - Observatoire de Paris, archived from the original on 23 February 2022, retrieved 30 June 2024 https://bibnum.obspm.fr/ark:/11287/z750B ↩

180. Johnson, George (28 March 1997). "Comets Breed Fear, Fascination and Web Sites". The New York Times. Retrieved 27 September 2009. When Halley's comet made its appearance in 1910, an Oklahoma religious group, known as the Sacred Followers, tried to sacrifice a virgin to ward off catastrophe. (They were stopped by the police.) The Daily Oklahoman newspaper quickly refuted the claim in their September 18 edition in an article on page 37. https://www.nytimes.com/1997/03/28/us/comets-breed-fear-fascination-and-web-sites.html?sec=health&spon=&pagewanted=all ↩

181. Paine, Albert Bigelow (1912). Mark Twain, a biography: the personal and literary life of Samuel Langhorne Clemens. Harper & Brothers. p. 1511. /wiki/Albert_Paine ↩

182. Metcalf, Miranda. "Mark Twain's birthday". Smithsonian Libraries. Archived from the original on 11 June 2010. Retrieved 16 December 2009. https://web.archive.org/web/20100611141141/http://smithsonianlibraries.si.edu/smithsonianlibraries/2009/11/mark-twains-birthday.html ↩

183. Gail S. Cleere (1985). A Magnificent Old Conflagration: Comet Halley in Washington D.C. and Elsewhere. Department of the Navy, U.S. Naval Observatory. p. 20. https://play.google.com/store/books/details?id=lYTvAAAAMAAJ&rdid=book-lYTvAAAAMAAJ&rdot=1 ↩

184. anonymous (1910). "The Death of Mark Twain". Chautauquan. The University of Virginia Library. Retrieved 16 December 2009. http://etext.virginia.edu/railton/sc_as_mt/mtobit5.html ↩

185. McCracken, Harry (5 October 1986). "One of the best animated films in recent years, a splendid job". Cinefantastique. Fourth Castle Micromedia. p. 108. Retrieved 7 July 2024. At the film's core, though, is a plot twist devised by the filmmakers themselves; it's Mark Twain himself who captains the zeppelin, in a suicidal mission to meet Halley's comet head-on and assure the truth of his famous prediction that his life would end with the comet's return. https://archive.org/details/cinefantastique_1970-2002/Cinefantastique%20Vol%2016%20No%204-5%20Oct%20%281986%29/page/n107/mode/1up?view=theater ↩

186. Bortle, John E. (13 January 2010). "The Great Daylight Comet of 1910". Sky & Telescope Magazine. Archived from the original on 4 February 2012. Retrieved 15 January 2010. /wiki/John_E._Bortle ↩

187. Bortle, John E. (1998). "The Bright Comet Chronicles". International Comet Quarterly. Retrieved 24 October 2010. /wiki/John_E._Bortle ↩

188. Broughton, R. Peter (1979). "The visibility of Halley's comet". Journal of the Royal Astronomical Society of Canada. 73: 24–36. Bibcode:1979JRASC..73...24B. /wiki/Bibcode_(identifier) ↩

189. "Comet Halley Summary". Jet Propulsion Laboratory. 1985. Archived from the original on 8 August 2008. Retrieved 11 July 2011. https://web.archive.org/web/20080808135012/http://er.jsc.nasa.gov/seh/halley.html ↩

190. "Australian Astronomy: Comets" (PDF). Australian Astronomical Association. 2004. Archived from the original (PDF) on 16 June 2005. Retrieved 2 December 2009. https://web.archive.org/web/20050616113415/http://www.astronomy.org.au/ngn/media/client/3110_factsheet_17.pdf ↩

191. "Last Chance For Good Comet-Viewing". Ocala Star-Banner. Associated Press. 1 April 1986. p. 14. Retrieved 2 December 2009. https://news.google.com/newspapers?nid=1356&dat=19860401&id=daxPAAAAIBAJ&pg=6812,63452 ↩

192. "Comet Halley Recovered". European Space Agency. 2006. Retrieved 16 January 2010. https://sci.esa.int/web/giotto/-/13795-comet-halley-recovered ↩

193. Browne, Malcolm W. (20 August 1985). "Telescope Builders See Halley's Comet From Vermont Hilltop". The New York Times. Retrieved 10 January 2008. (Horizons shows the nucleus @ APmag +20.5; the coma up to APmag +14.3) /wiki/Malcolm_Browne ↩

194. "First Naked-Eye Sighting of Halley's Comet Reported". New York Times. 12 November 1985. Archived from the original on 11 May 2011. Retrieved 21 July 2010. https://web.archive.org/web/20110511131818/http://pqasb.pqarchiver.com/latimes/access/64571529.html?dids=64571529:64571529&FMT=ABS&FMTS=ABS:FT&type=current&date=Nov+12,+1985&author=&pub=Los+Angeles+Times+(pre-1997+Fulltext)&desc=First+Naked-Eye+Sighting+of+Halley%27s+Comet+Reported&pqatl=google ↩

195. Keller, Horst Uwe; Britt, Daniel; Buratti, Bonnie J.; Thomas, Nicolas (2005). "In Situ Observations of Cometary Nuclei". In Festou, Michel; Keller, Horst Uwe; Weaver, Harold A. (eds.). Comets II. University of Arizona Press. pp. 211–222. ISBN 978-0-8165-2450-1. Archived (PDF) from the original on 1 July 2024. 978-0-8165-2450-1 ↩

196. Keller, Horst Uwe; Britt, Daniel; Buratti, Bonnie J.; Thomas, Nicolas (2005). "In Situ Observations of Cometary Nuclei". In Festou, Michel; Keller, Horst Uwe; Weaver, Harold A. (eds.). Comets II. University of Arizona Press. pp. 211–222. ISBN 978-0-8165-2450-1. Archived (PDF) from the original on 1 July 2024. 978-0-8165-2450-1 ↩

197. "Suisei". Japan Aerospace Exploration Agency. 2008. Archived from the original on 14 January 2013. Retrieved 2 December 2009. https://web.archive.org/web/20130114204755/http://www.isas.ac.jp/e/enterp/missions/suisei.shtml ↩

198. Boyarchuk, Alexander A.; Grinin, Vladimir P.; Zvereva, A. M.; Petrov, Peter P.; Sheikhet, A. I. (1986). "A model for the coma of Comet Halley, based on the Astron ultraviolet spectrophotometry". Pis'ma v Astronomicheskii Zhurnal (in Russian). 12: 291–296. Bibcode:1986PAZh...12..696B. /wiki/Alexandr_Boyarchuk ↩

199. Murdin, Paul (2000). "International Cometary Explorer (ICE)". Encyclopedia of Astronomy and Astrophysics. Institute of Physics Publishing. Bibcode:2000eaa..bookE4650.. doi:10.1888/0333750888/4650. hdl:2060/19920003890. ISBN 0-333-75088-8. 0-333-75088-8 ↩

200. "In Depth | ISEE-3/ICE". NASA Solar System Exploration. 8 December 2017. Retrieved 25 June 2021. https://solarsystem.nasa.gov/missions/isee-3-ice/in-depth ↩

201. Siddiqi 2018, pp. 149–150. - Siddiqi, Asif A. (2018). Beyond Earth: A Chronicle of Deep Space Exploration. United States: NASA History Program Office. pp. 149–150. ISBN 9781626830424. https://www.nasa.gov/connect/ebooks/beyond_earth_detail.html ↩

202. "Spartan 203 (Spartan Halley, HCED)". space.skyrocket.de. Retrieved 6 September 2011. http://space.skyrocket.de/doc_sdat/spartan-203.htm ↩

203. "STS-51L". NASA Kennedy Space Center. 5 December 2005. Retrieved 7 January 2010. https://www.nasa.gov/mission_pages/shuttle/shuttlemissions/archives/sts-51L.html ↩

204. Shayler & Burgess 2007, pp. 431–476. - Shayler, David J.; Burgess, Colin (2007). "Ending of Eras". NASA's Scientist-Astronauts. Praxis. ISBN 978-0-387-21897-7. Retrieved 7 January 2009. https://books.google.com/books?id=TweEC3h633AC&pg=PA431 ↩

205. "STS-35 (38)". NASA. Archived from the original on 14 August 2011. Retrieved 7 January 2010. https://web.archive.org/web/20110814122631/http://science.ksc.nasa.gov/shuttle/missions/sts-35/mission-sts-35.html ↩

206. "Hirohito up before dawn to see comet". Upi. 18 March 1986. Retrieved 21 August 2024. https://www.upi.com/Archives/1986/03/18/Hirohito-up-before-dawn-to-see-comet/4509511506000/ ↩

207. "Hirohito up before dawn to see comet". Upi. 18 March 1986. Retrieved 21 August 2024. https://www.upi.com/Archives/1986/03/18/Hirohito-up-before-dawn-to-see-comet/4509511506000/ ↩

208. Gronkowski, P. (2002). "Outbursts of comets—the case of 1P/Halley". Planetary and Space Science. 50 (3): 247–256. Bibcode:2002P&SS...50..247G. doi:10.1016/S0032-0633(02)00003-X. https://www.sciencedirect.com/science/article/abs/pii/S003206330200003X ↩

209. Brandt, John C. (February 2018). "Halley's Comet". AccessScience. McGraw Hill. doi:10.1036/1097-8542.305800. /wiki/Doi_(identifier) ↩

210. West, R. M.; Hainaut, O.; Smette, A. (June 1991). "Post-perihelion observations of P/Halley. III - an outburst at R=14.3 AU". Astronomy and Astrophysics. 246 (2): L77 – L80. Bibcode:1991A&A...246L..77W. /wiki/Richard_Martin_West ↩

211. Prialnik, Dina; Bar-Nun, Akiva (1992). "Crystallization of amorphous ice as the cause of Comet P/Halley's outburst at 14 AU". Astronomy and Astrophysics. 258 (2): L9 – L12. Bibcode:1992A&A...258L...9P. PMID 11538062. /wiki/Bibcode_(identifier) ↩

212. Gronkowski, P. (2002). "Outbursts of comets—the case of 1P/Halley". Planetary and Space Science. 50 (3): 247–256. Bibcode:2002P&SS...50..247G. doi:10.1016/S0032-0633(02)00003-X. https://www.sciencedirect.com/science/article/abs/pii/S003206330200003X ↩

213. Gronkowski, P. (2002). "Outbursts of comets—the case of 1P/Halley". Planetary and Space Science. 50 (3): 247–256. Bibcode:2002P&SS...50..247G. doi:10.1016/S0032-0633(02)00003-X. https://www.sciencedirect.com/science/article/abs/pii/S003206330200003X ↩

214. Hughes, David W. (1991). "Comet Halley's outburst". Monthly Notices of the Royal Astronomical Society. 251: 26–29. doi:10.1093/mnras/251.1.26P. https://adsabs.harvard.edu/pdf/1991MNRAS.251P..26H ↩

215. Gronkowski, P. (2002). "Outbursts of comets—the case of 1P/Halley". Planetary and Space Science. 50 (3): 247–256. Bibcode:2002P&SS...50..247G. doi:10.1016/S0032-0633(02)00003-X. https://www.sciencedirect.com/science/article/abs/pii/S003206330200003X ↩

216. "New Image of Comet Halley in the Cold". European Southern Observatory. 1 September 2003. Retrieved 26 February 2018. https://www.eso.org/public/news/eso0328/ ↩

217. "New Image of Comet Halley in the Cold". European Southern Observatory. 1 September 2003. Retrieved 26 February 2018. https://www.eso.org/public/news/eso0328/ ↩

218. "Horizons Batch for 1P/Halley (90000030) on 2023-Dec-09" (Aphelion occurs when rdot flips from positive to negative). JPL Horizons. Archived from the original on 1 July 2022. Retrieved 1 July 2022. (JPL#73 Soln.date: 2022-Jun-07) https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000030%27&START_TIME=%272023-Dec-09%27&STOP_TIME=%272023-Dec-10%27&STEP_SIZE=%271%20hours%27&QUANTITIES=%2719,22%27 ↩

219. DNews (3 September 2013). "Let's Plan For a Rendezvous With Halley's Comet". Seeker. Archived from the original on 28 November 2022. Retrieved 29 October 2019. https://web.archive.org/web/20221128171635/https://www.seeker.com/lets-plan-for-a-rendezvous-with-halleys-comet-1767783657.html ↩

220. "Horizons Batch for 1P/Halley (90000030) on 2061-Jul-28" (Perihelion occurs when rdot flips from negative to positive @ 2061-Jul-28 17:20 UT). JPL Horizons. Archived from the original on 27 May 2022. Retrieved 28 June 2022. (JPL#73 Soln.date: 2022-Jun-07) https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000030%27&START_TIME=%272061-Jul-28%2017:00%27&STOP_TIME=%272061-Jul-28%2018:00%27&STEP_SIZE=%271%20min%27&QUANTITIES=%2719%27 ↩

221. Kinoshita, Kazuo (3 October 2003). "1P/Halley past, present and future orbital elements". Comet Orbit. http://jcometobs.web.fc2.com/pcmtn/0001p.htm ↩

222. "Why we include a preview of Halley's next apparition after our current comet show, Comets and Discovery" (PDF). Abrams Planetarium. Archived (PDF) from the original on 16 May 2024. Retrieved 9 July 2024. https://www.abramsplanetarium.org/Programs/CaseForCometHalley2061.pdf ↩

223. "JPL Small-Body Database Browser: 1P/Halley" (11 January 1994 last obs). Jet Propulsion Laboratory. Archived from the original on 27 April 2015. Retrieved 28 June 2022. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1P&view=OPC ↩

224. Odenwald, Sten. "When will Halley's Comet return?". NASA. Archived from the original on 6 August 2011. Retrieved 29 November 2009. /wiki/Sten_Odenwald ↩

225. "JPL Small-Body Database Browser: 1P/Halley" (11 January 1994 last obs). Jet Propulsion Laboratory. Archived from the original on 27 April 2015. Retrieved 28 June 2022. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1P&view=OPC ↩

226. "Horizons Batch for 1P/Halley (90000030) on 2134-Mar-27" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Archived from the original on 28 June 2022. Retrieved 28 June 2022. (JPL#73 Soln.date: 2022-Jun-07) https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000030%27&START_TIME=%272134-Mar-24%27&STOP_TIME=%272134-Mar-30%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719%27 ↩

227. Kinoshita, Kazuo (3 October 2003). "1P/Halley past, present and future orbital elements". Comet Orbit. http://jcometobs.web.fc2.com/pcmtn/0001p.htm ↩

228. "JPL Small-Body Database Browser: 1P/Halley" (11 January 1994 last obs). Jet Propulsion Laboratory. Archived from the original on 27 April 2015. Retrieved 28 June 2022. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1P&view=OPC ↩

229. Odenwald, Sten. "When will Halley's Comet return?". NASA. Archived from the original on 6 August 2011. Retrieved 29 November 2009. /wiki/Sten_Odenwald ↩

230. "JPL Small-Body Database Browser: 1P/Halley" (11 January 1994 last obs). Jet Propulsion Laboratory. Archived from the original on 27 April 2015. Retrieved 28 June 2022. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1P&view=OPC ↩

231. "Comet names and designations". International Comet Quarterly. Retrieved 20 January 2011. http://www.icq.eps.harvard.edu/names1.html ↩

232. Schmude 2010, p. 3. - Schmude, Richard M. (2010). Comets and How to Observe Them. Springer. p. 3. ISBN 978-1-4419-5790-0. https://books.google.com/books?id=WemDVdrPIIUC&pg=PA3 ↩

233. Marsden, Brian G.; Williams, Gareth V. (1996). "Catalogue of Cometary Orbits 1996. 11th edition". Catalogue of Cometary Orbits. International Astronomical Union. Bibcode:1996cco..book.....M. /wiki/Brian_G._Marsden ↩

234. Sitarski, G. (1988). "On the nongravitational motion of Comet P/Halley". Acta Astronomica. 38 (3): 253–268. Bibcode:1988AcA....38..253S. https://articles.adsabs.harvard.edu/pdf/1988AcA....38..253S ↩

235. Sitarski, G. (1988). "On the nongravitational motion of Comet P/Halley". Acta Astronomica. 38 (3): 253–268. Bibcode:1988AcA....38..253S. https://articles.adsabs.harvard.edu/pdf/1988AcA....38..253S ↩

236. Chang, Y. C. (1979). "Halley's comet: Tendencies in its orbital evolution and its ancient history". Chinese Astronomy. 3 (1): 120–131. Bibcode:1979ChA.....3..120C. doi:10.1016/0146-6364(79)90084-7. /wiki/Zhang_Yuzhe ↩

237. Chang, Y. C. (1979). "Halley's comet: Tendencies in its orbital evolution and its ancient history". Chinese Astronomy. 3 (1): 120–131. Bibcode:1979ChA.....3..120C. doi:10.1016/0146-6364(79)90084-7. /wiki/Zhang_Yuzhe ↩

238. "1P/Halley Orbit". Minor Planet Center. Archived from the original on 4 July 2022. Retrieved 28 June 2022. (epoch 451 is 79.29 years) https://www.minorplanetcenter.net/db_search/show_object?object_id=1P ↩

239. Yeomans, Donald Keith; Rahe, Jürgen; Freitag, Ruth S. (1986). "The History of Comet Halley". Journal of the Royal Astronomical Society of Canada. 80: 81. Bibcode:1986JRASC..80...62Y. /wiki/Bibcode_(identifier) ↩

240. Prior to the invention of the telescope in the 17th century, this is the time when the comet was visible to the naked eye. /wiki/Invention_of_the_telescope ↩

241. Yeomans, Donald Keith (1998). "Great Comets in History". Jet Propulsion Laboratory. Retrieved 15 March 2007. https://ssd.jpl.nasa.gov/?great_comets ↩

242. Chang, Y. C. (1979). "Halley's comet: Tendencies in its orbital evolution and its ancient history". Chinese Astronomy. 3 (1): 120–131. Bibcode:1979ChA.....3..120C. doi:10.1016/0146-6364(79)90084-7. /wiki/Zhang_Yuzhe ↩

243. Ridpath, Ian (1985). "Returns of Halley's Comet". Revised extracts from "A Comet Called Halley". Cambridge University Press. Retrieved 15 January 2022. /wiki/Ian_Ridpath ↩

244. Chambers, George F. (1909). The Story of the Comets. The Clarenden Press. p. 123. https://archive.org/details/b31349596 ↩

245. Milbrath 1999, p. 684. - Milbrath, Susan (1999). Star Gods of the Maya: Astronomy in Art, Folklore, and Calendars. The Linda Schele Series in Maya and Pre-Columbian Studies. University of Texas Press. doi:10.7560/752252. ISBN 978-0-292-79793-2. https://books.google.com/books?id=cUL3DAAAQBAJ&pg=PA251 ↩

246. "Horizons Batch for 1P/Halley (90000015) on 837AD-Apr-10" (Earth approach occurs when deldot flips from negative to positive @ 837-Apr-10 12:13). JPL Horizons. Archived from the original on 30 June 2022. Retrieved 29 June 2022. (SAO/837) https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000015%27&START_TIME=%27837AD-Apr-10%2012:00%27&STOP_TIME=%27837AD-Apr-10%2012:30%27&STEP_SIZE=%271%20minutes%27&QUANTITIES=%2719,20,23%27 ↩

247. Dumouchel, Etienne (1836). "Vermischte Nachrichten". Astronomische Nachrichten. 13 (1): 16. /wiki/Astronomische_Nachrichten ↩

248. "JPL Small-Body Database Browser: 1P/Halley" (11 January 1994 last obs). Jet Propulsion Laboratory. Archived from the original on 27 April 2015. Retrieved 28 June 2022. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1P&view=OPC ↩

249. "New Image of Comet Halley in the Cold". European Southern Observatory. 1 September 2003. Retrieved 26 February 2018. https://www.eso.org/public/news/eso0328/ ↩

250. "Horizons Batch for 1P/Halley (90000030) on 2061-Jul-28" (Perihelion occurs when rdot flips from negative to positive @ 2061-Jul-28 17:20 UT). JPL Horizons. Archived from the original on 27 May 2022. Retrieved 28 June 2022. (JPL#73 Soln.date: 2022-Jun-07) https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000030%27&START_TIME=%272061-Jul-28%2017:00%27&STOP_TIME=%272061-Jul-28%2018:00%27&STEP_SIZE=%271%20min%27&QUANTITIES=%2719%27 ↩

251. Kinoshita, Kazuo (3 October 2003). "1P/Halley past, present and future orbital elements". Comet Orbit. http://jcometobs.web.fc2.com/pcmtn/0001p.htm ↩

252. "Horizons Batch for 1P/Halley (90000030) on 2061-Jul-28" (Perihelion occurs when rdot flips from negative to positive @ 2061-Jul-28 17:20 UT). JPL Horizons. Archived from the original on 27 May 2022. Retrieved 28 June 2022. (JPL#73 Soln.date: 2022-Jun-07) https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000030%27&START_TIME=%272061-Jul-28%2017:00%27&STOP_TIME=%272061-Jul-28%2018:00%27&STEP_SIZE=%271%20min%27&QUANTITIES=%2719%27 ↩

253. Kinoshita, Kazuo (3 October 2003). "1P/Halley past, present and future orbital elements". Comet Orbit. http://jcometobs.web.fc2.com/pcmtn/0001p.htm ↩

254. "JPL Small-Body Database Browser: 1P/Halley" (11 January 1994 last obs). Jet Propulsion Laboratory. Archived from the original on 27 April 2015. Retrieved 28 June 2022. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1P&view=OPC ↩

255. "Horizons Batch for 1P/Halley (90000030) on 2134-Mar-27" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Archived from the original on 28 June 2022. Retrieved 28 June 2022. (JPL#73 Soln.date: 2022-Jun-07) https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000030%27&START_TIME=%272134-Mar-24%27&STOP_TIME=%272134-Mar-30%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719%27 ↩

256. Kinoshita, Kazuo (3 October 2003). "1P/Halley past, present and future orbital elements". Comet Orbit. http://jcometobs.web.fc2.com/pcmtn/0001p.htm ↩

257. "JPL Small-Body Database Browser: 1P/Halley" (11 January 1994 last obs). Jet Propulsion Laboratory. Archived from the original on 27 April 2015. Retrieved 28 June 2022. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1P&view=OPC ↩

258. "Horizons Batch for 1P/Halley (90000030) on 2209-Feb-03 and 2209-Apr-10" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Archived from the original on 30 June 2022. Retrieved 30 June 2022. (JPL#73 Soln.date: 2022-Jun-07) https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000030%27&START_TIME=%272209-Feb-01%27&STOP_TIME=%272209-Apr-20%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719,20,23%27 ↩

259. "Horizons Batch for 1P/Halley (90000030) on 2209-Feb-03 and 2209-Apr-10" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Archived from the original on 30 June 2022. Retrieved 30 June 2022. (JPL#73 Soln.date: 2022-Jun-07) https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2790000030%27&START_TIME=%272209-Feb-01%27&STOP_TIME=%272209-Apr-20%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719,20,23%27 ↩