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<h2 id="first-20-minutes">First 20 minutes</h2> <h3>Planck epoch</h3> <ul><li>c. 0 seconds (13.799 ± 0.021 <a href="/facts/Bya_(unit)/51V242hh">Gya</a>): <a href="/facts/Planck_epoch/ezBKAdjy">Planck epoch</a> begins: <a href="/facts/Big_Bang/I5T1vTnv">Big Bang</a> occurs in which ordinary space and time develop out of a primeval state described by a <a href="/facts/Quantum_gravity/t7whBMNE">quantum theory of gravity</a> or "<a href="/facts/Theory_of_everything/rpossh4t">Theory of everything</a>". All matter and energy of the universe is contained in a hot, dense point (<a href="/facts/Gravitational_singularity/BptlItux">gravitational singularity</a>)</li></ul> <h3>Grand unification epoch</h3> <ul><li>c. 10−43 seconds: <a href="/facts/Gravity/bqAN7DdQ">Gravity</a> separates and begins operating on the universe—the remaining fundamental forces stabilize into the <a href="/facts/Electronuclear_force/UVHj76XX">electronuclear force</a>, also known as the Grand Unified Force or <a href="/facts/Grand_Unified_Theory/UVHj76XX">Grand Unified Theory</a> (GUT), mediated by (the hypothetical) <a href="/facts/X_and_Y_bosons/TJwvcbE3">X and Y bosons</a> which allow early <a href="/facts/Matter/osyc04UN">matter</a> at this stage to fluctuate between <a href="/facts/Baryon/QFwAUWK2">baryon</a> and <a href="/facts/Lepton/X4a6MGop">lepton</a> states.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a></li></ul> <h3>Inflation</h3> <ul><li>c. 10−35 seconds: <a href="/facts/Cosmic_inflation/SujXx3aD">inflation</a>, expands the universe by a factor of the order of 1026 over a time of the order of 10−33 to 10−32 seconds. The universe is <a href="/facts/Supercooled/VdSgseJU">supercooled</a> from about 1027 down to 1022 kelvin.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a></li> <li>c. 10−32 seconds: Cosmic inflation ends.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>: 193 The familiar <a href="/facts/Elementary_particle/CTFDM97U">elementary particles</a> now form as a soup of hot ionized gas called <a href="/facts/Quark%E2%80%93gluon_plasma/TQ8RPydR">quark–gluon plasma</a>;</li></ul> <h3>Quark epoch</h3> <ul><li>c. 10−12 seconds: <a href="/facts/Cosmological_phase_transition/4YwSqbeE">Electroweak phase transition</a>: The <a href="/facts/Weak_nuclear_force/f6upmKMs">weak nuclear force</a> is now a short-range force as it separates from <a href="/facts/Electromagnetic_force/oAkmALHT">electromagnetic force</a>, so matter particles can <a href="/facts/Higgs_mechanism/Vs5Cbxyy">acquire mass</a> and interact with the <a href="/facts/Higgs_Field/3LAYXfft">Higgs Field</a>. The <a href="/facts/Quark%E2%80%93gluon_plasma/TQ8RPydR">quark–gluon plasma</a> persists (<a href="/facts/Quark_epoch/qWGR0WC9">Quark epoch</a>). The universe cools to 1015 kelvin.</li></ul> <h3>Quark-hadron transition</h3> <ul><li>c. 10−6 seconds: As the universe cools to about 1010 kelvin, a quark-hadron transition takes place in which quarks become <a href="/facts/Color_confinement/W3XjqMAS">confined</a> in more complex particles—<a href="/facts/Hadrons/C0sd1zty">hadrons</a>.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>: 305 </li></ul> <h3>Lepton epoch</h3> <ul><li>c. 1 second: <a href="/facts/Lepton_epoch/5cuMRN1L">Lepton epoch</a> begins: The universe cools to 109 kelvin. At this temperature, the hadrons and antihadrons annihilate each other, leaving behind <a href="/facts/Leptons/X4a6MGop">leptons</a> and <a href="/facts/Antileptons/X4a6MGop">antileptons</a> – possible disappearance of <a href="/facts/Antiquarks/hwuuVkV5">antiquarks</a>. Gravity governs the expansion of the universe: neutrinos <a href="/facts/Decoupling_(cosmology)/Kj6FbgLf">decouple</a> from matter creating a <a href="/facts/Cosmic_neutrino_background/J9jzIPC0">cosmic neutrino background</a>.</li></ul> <h3>Photon epoch</h3> <ul><li>c. 10 seconds: <a href="/facts/Photon_epoch/y6QRD98j">Photon epoch</a> begins: Most leptons and antileptons annihilate each other. As <a href="/facts/Electrons/L0KBo5cW">electrons</a> and <a href="/facts/Positrons/HgV4zBzA">positrons</a> annihilate, a small number of unmatched electrons are left over – disappearance of the positrons.</li> <li>c. 10 seconds: Universe dominated by photons of radiation – ordinary matter particles are coupled to <a href="/facts/Light/jeofpMn4">light</a> and radiation.</li> <li>c. 3 minutes: Primordial <a href="/facts/Nucleosynthesis/F9MIeADF">nucleosynthesis</a>: <a href="/facts/Nuclear_fusion/hP0gLDqj">nuclear fusion</a> begins as <a href="/facts/Lithium/7vXX6BWA">lithium</a> and heavy hydrogen (<a href="/facts/Deuterium/Bv4wfCkw">deuterium</a>) and <a href="/facts/Helium_nuclei/dzNMs9WP">helium nuclei</a> form from protons and neutrons.</li> <li>c. 20 minutes: Primordial nucleosynthesis ceases</li></ul> <h2 id="matter-era">Matter era</h2> <h3>Matter and radiation equivalence</h3> <ul><li>c. 47,000 years (<i>z</i> = 3600): <a href="/facts/Matter/osyc04UN">Matter</a> and radiation equivalence</li> <li>c. 70,000 years: As the temperature falls, <a href="/facts/Jeans_length/VBmcPj7Y">gravity overcomes pressure</a> allowing first aggregates of matter to form.</li></ul> <h3>Cosmic Dark Age</h3> <ul><li>c. 370,000 years (<i>z</i> = 1,100): The "<a href="/facts/Dark_Ages_(cosmology)/ezBKAdjy">Dark Ages</a>" is the period between <a href="/facts/Decoupling_(cosmology)/Kj6FbgLf">decoupling</a>, when the universe first becomes transparent, until the formation of the first <a href="/facts/Star/PFbd6ICx">stars</a>. <a href="/facts/Recombination_(cosmology)/cUGysC0q">Recombination</a>: electrons combine with nuclei to form <a href="/facts/Atoms/FoQ4kGN5">atoms</a>, mostly <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a> and <a href="/facts/Helium/yRul93TG">helium</a>. Ordinary matter particles decouple from radiation. The photons present during the decoupling are the same photons seen in the <a href="/facts/Cosmic_microwave_background/ThB2HkLS">cosmic microwave background</a> (CMB) radiation.</li> <li>c. 10–17 million years: The "Dark Ages" span a period during which the temperature of <a href="/facts/Cosmic_microwave_background_radiation/ThB2HkLS">cosmic microwave background radiation</a> cooled from some 4,000 K (3,730 °C; 6,740 °F) down to about 60 K (−213.2 °C; −351.7 °F).</li></ul> <h3>Reionization</h3> <ul><li>c. 100 million years: Gravitational collapse: ordinary matter particles fall into the structures created by dark matter. <a href="/facts/Reionization/tfqf1Ny9">Reionization</a> begins: smaller (<a href="/facts/Stars/PFbd6ICx">stars</a>) and larger non-linear structures (<a href="/facts/Quasars/HS96328l">quasars</a>) begin to take shape – their <a href="/facts/Ultraviolet/kncBUqn5">ultraviolet</a> light ionizes remaining neutral gas.</li> <li>200–300 million years: First stars begin to shine: Because many are <a href="/facts/Population_III_stars/8ur1qDRK">Population III stars</a> (some <a href="/facts/Population_II_stars/8ur1qDRK">Population II stars</a> are accounted for at this time) they are much bigger and hotter and their life cycle is fairly short. Unlike later generations of stars, these stars are metal free. <a href="/facts/Reionization/tfqf1Ny9">Reionization</a> begins, with the absorption of certain wavelengths of light by neutral hydrogen creating <a href="/facts/Gunn%E2%80%93Peterson_trough/FNY3IvSu">Gunn–Peterson troughs</a>. The resulting ionized gas (especially free electrons) in the <a href="/facts/Warm%E2%80%93hot_intergalactic_medium/IhGdCGhR">intergalactic medium</a> causes some <a href="/facts/Reionization/tfqf1Ny9">scattering</a> of light, but with much lower opacity than before recombination due the expansion of the universe and clumping of gas into galaxies.</li> <li>200 million years: The <a href="/facts/List_of_oldest_stars/8lh1MQjd">oldest-known star</a> (confirmed) – <a href="/facts/SMSS_J031300.36%E2%88%92670839.3/BwLjF3Fh">SMSS J031300.36−670839.3</a>, forms.</li> <li>300 million years: First large-scale astronomical objects, <a href="/facts/Protogalaxies/QvUW6nrC">protogalaxies</a> and <a href="/facts/Quasars/HS96328l">quasars</a> may have begun forming. As Population III stars continue to burn, <a href="/facts/Stellar_nucleosynthesis/qEQJdJe6">stellar nucleosynthesis</a> operates – stars burn mainly by fusing hydrogen to produce more helium in what is referred to as the <a href="/facts/Main_sequence/DJ3Wq8kd">main sequence</a>. Over time these stars are forced to fuse helium to produce <a href="/facts/Carbon/ukrgQexo">carbon</a>, <a href="/facts/Oxygen/acyn6o8r">oxygen</a>, <a href="/facts/Silicon/cgWx0hdr">silicon</a> and other heavy elements up to <a href="/facts/Iron/QK1JYy8E">iron</a> on the periodic table. These elements, when seeded into neighbouring gas clouds by <a href="/facts/Supernova/Pfo2J23l">supernova</a>, will lead to the formation of more <a href="/facts/Population_II/8ur1qDRK">Population II</a> stars (metal poor) and <a href="/facts/Gas_giants/pmF6KztG">gas giants</a>.</li> <li>320 million years (<i>z</i> = 13.3): <a href="/facts/HD1/UCqsUPXE">HD1</a>, the oldest-known spectroscopically-confirmed <a href="/facts/Galaxy/zCyUvEf7">galaxy</a>, forms.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></li> <li>380 million years: <a href="/facts/UDFj-39546284/JLQLkhth">UDFj-39546284</a> forms, current record holder for unconfirmed oldest-known <a href="/facts/Quasar/HS96328l">quasar</a>.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></li> <li>600 million years: <a href="/facts/HE_1523-0901/hA1zzXVB">HE 1523-0901</a>, the oldest star found producing <a href="/facts/Neutron_capture/elsFpM12">neutron capture</a> elements forms, marking a new point in ability to detect stars with a telescope.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></li> <li>630 million years (<i>z</i> = 8.2): <a href="/facts/GRB_090423/jbvvdsK1">GRB 090423</a>, the oldest <a href="/facts/Gamma-ray_burst/oRRU6Fhn">gamma-ray burst</a> recorded suggests that supernovas may have happened very early on in the evolution of the Universe<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a></li></ul> <h3>Galaxy epoch</h3> <ul><li>< 1 billion years, (13 <a href="/facts/Gya_(unit)/5E7foypY">Gya</a>): first stars in the central bar portion of the Milky Way are born,<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a></li> <li>2.6 billion years (11 <a href="/facts/Gya_(unit)/5E7foypY">Gya</a>): first stars in the thick disk region of the Milky Way are formed.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a></li> <li>4 billion years (10 <a href="/facts/Gya_(unit)/5E7foypY">Gya</a>): <a href="/facts/Gaia_Enceladus/7dCbvl6c">Gaia Enceladus</a> merges into Milky Way.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a></li> <li>5 or 6 billion years, (8 or 9 <a href="/facts/Gya_(unit)/5E7foypY">Gya</a>): first stars in the thin disk region of the Milky Way are formed.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a></li></ul> <h3>Acceleration</h3> <ul><li>8.8 billion years (5 Gya, <i>z</i> = 0.5): <a href="/facts/Accelerating_expansion_of_the_universe/F7X1PAMq">Acceleration</a>: <a href="/facts/Dark-energy_dominated_era/hN9JlB3v">dark-energy dominated era</a> begins, following the <a href="/facts/Matter-dominated_era/hN9JlB3v">matter-dominated era</a> during which cosmic expansion was slowing down.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a></li></ul> <h2 id="epochs-of-the-formation-of-the-solar-system">Epochs of the formation of the Solar System</h2> <p class="note">Main article: <a href="/facts/Formation_and_evolution_of_the_Solar_System/cgElXHpM">Formation and evolution of the Solar System</a></p> <ul><li>9.2 billion years (4.6–4.57 Gya): Primal supernova, possibly triggers the <a href="/facts/Formation_of_The_Solar_System/cgElXHpM">formation of The Solar System</a>.</li> <li>9.2318 billion years (4.5682 Gya): <a href="/facts/Sun/CadPCVHh">Sun</a> forms – Planetary nebula begins accretion of planets.</li> <li>9.23283 billion years (4.56717–4.55717 Gya): Four <a href="/facts/Jovian_planets/PjSfFuUF">Jovian planets</a> (<a href="/facts/Jupiter/95m7XjMT">Jupiter</a>, <a href="/facts/Saturn/D54LcGJ9">Saturn</a>, <a href="/facts/Uranus/x7YwT1ar">Uranus</a>, <a href="/facts/Neptune/1eucwHIC">Neptune</a>) evolve around the Sun.</li> <li>9.257 billion years (4.543–4.5 Gya): Solar System of Eight planets, four terrestrial (<a href="/facts/Mercury_(planet)/lVa1GIyX">Mercury</a>, <a href="/facts/Venus/pADnueP6">Venus</a>, <a href="/facts/Earth/HLLmDfj0">Earth</a>, <a href="/facts/Mars/AQGtVvz0">Mars</a>) evolve around the Sun. Because of accretion many smaller planets form orbits around the proto-Sun some with conflicting orbits – early heavy bombardment begins. A large planetoid strikes Mercury, stripping it of outer envelope of original crust and mantle, leaving the planet's core exposed – Mercury's iron content is notably high.</li> <li>9.266 billion years (4.533 Gya): Formation of Earth-<a href="/facts/Moon/zKHqEMPb">Moon</a> system following <a href="/facts/Giant_impact/x2cw2Xxn">giant impact</a> by hypothetical planetoid <a href="/facts/Theia_(planet)/wNcb6LB9">Theia (planet)</a>. Moon's gravitational pull helps stabilize Earth's fluctuating <a href="/facts/Axis_of_rotation/PGcg3IY5">axis of rotation</a>.</li> <li>9.271 billion years (4.529 Gya): Major collision with a pluto-sized planetoid establishes the <a href="/facts/Martian_dichotomy/11Ixk04I">Martian dichotomy</a> on Mars</li> <li>9.3 billion years (4.5 Gya): Sun becomes a main sequence yellow star: formation of the <a href="/facts/Oort_cloud/wdP3VNxd">Oort cloud</a> and <a href="/facts/Kuiper_belt/IvLzYp5P">Kuiper belt</a></li> <li>9.396 billion years (4.404 Gya): <a href="/facts/Liquid_water/0lkXnJPK">Liquid water</a> may have existed on the surface of the <a href="/facts/Earth/HLLmDfj0">Earth</a></li> <li>9.7 billion years (4.1 Gya): Resonance in Jupiter and Saturn's orbits moves Neptune out into the Kuiper belt causing a disruption among asteroids and comets there. As a result, <a href="/facts/Late_Heavy_Bombardment/PBUlnPJX">Late Heavy Bombardment</a> batters the inner Solar System. Meteorite impact creates the <a href="/facts/Hellas_Planitia/sX6et9v8">Hellas Planitia</a> on Mars, the largest unambiguous structure on the planet.</li> <li>10.4 billion years (3.5 Gya): Earliest fossil traces of life on Earth (<a href="/facts/Stromatolite/Wr208p5m">stromatolites</a>)</li> <li>10.6 billion years (3.2 Gya): Martian climate thins to its present density: groundwater stored in upper crust (megaregolith) begins to freeze, forming thick cryosphere overlying deeper zone of liquid water – dry ices composed of frozen carbon dioxide form</li> <li>10.8 billion years (3 Gya): <a href="/facts/Beethoven_Basin/MNnlMbkm">Beethoven Basin</a> forms on Mercury – unlike many basins of similar size on the Moon, Beethoven is not multi ringed and ejecta buries crater rim and is barely visible</li> <li>11.6 billion years (2.2 Gya): Last great tectonic period in Martian geologic history: <a href="/facts/Valles_Marineris/Yn3xDfDl">Valles Marineris</a>, largest canyon complex in the Solar System, forms – although some suggestions of thermokarst activity or even water erosion, it is suggested Valles Marineris is rift fault.</li></ul> <h2 id="recent-history">Recent history</h2> <ul><li>11.8 billion years (2 Gya): <a href="/facts/Olympus_Mons/wnnlS99Q">Olympus Mons</a>, the largest volcano in the Solar System, is formed</li> <li>12.1 billion years (1.7 Gya): <a href="/facts/Sagittarius_Dwarf_Spheroidal_Galaxy/9IfJCbtl">Sagittarius Dwarf Spheroidal Galaxy</a> captured into an orbit around Milky Way Galaxy</li> <li>12.7 billion years (1.1 Gya): <a href="/facts/Copernican_period/39uxDII5">Copernican Period</a> begins on Moon: defined by impact craters that possess bright optically immature ray systems</li> <li>12.8 billion years (1 Gya): Interactions between Andromeda and its companion galaxies Messier 32 and Messier 110. Galaxy collision with Messier 82 forms its patterned spiral disc: galaxy interactions between NGC 3077 and Messier 81; Saturn's moon <a href="/facts/Titan_(moon)/lg0l9PCH">Titan</a> begins evolving the recognisable surface features that include rivers, lakes, and deltas</li> <li>13 billion years (800 <a href="/facts/Mya_(unit)/DXcnXuAw">Mya</a>): <a href="/facts/Copernicus_(lunar_crater)/SH2l51TU">Copernicus (lunar crater)</a> forms from the impact on the Lunar surface in the area of Oceanus Procellarum – has terrace inner wall and 30 km wide, sloping rampart that descends nearly a kilometre to the surrounding mare</li> <li>13.175 billion years (625 Mya): formation of <a href="/facts/Hyades_(star_cluster)/XmNqJhqA">Hyades</a> star cluster: consists of a roughly spherical group of hundreds of stars sharing the same age, place of origin, chemical content and motion through space</li> <li>13.2 billion years (600 Mya): Whirlpool Galaxy collides with <a href="/facts/NGC_5195/wKVlLzk2">NGC 5195</a> forming a present connected galaxy system. <a href="/facts/HD_189733_b/Cxur2pca">HD 189733 b</a> forms around parent star <a href="/facts/HD_189733/GPLH1z3D">HD 189733</a>: the first planet to reveal the climate, organic constituencies, even colour (blue) of its atmosphere</li> <li>13.6–13.5 billion years (300-200 Mya): <a href="/facts/Sirius/sHCkClse">Sirius</a>, the brightest star in the Earth's sky, forms.</li> <li>13.7 billion years (100 Mya): Formation of <a href="/facts/Pleiades/tjwtx82z">Pleiades</a> Star Cluster</li> <li>13.780 billion years (20 Mya): Possible formation of <a href="/facts/Orion_Nebula/6VWbcqzL">Orion Nebula</a></li> <li>13.792 billion years (7.6 Mya): <a href="/facts/Betelgeuse/BsD9Ap7C">Betelgeuse</a> forms.</li> <li>13.8 billion years (Without uncertainties): Present day.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></li></ul> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Chronology_of_the_universe/ezBKAdjy">Chronology of the universe</a></li> <li><a href="/facts/Formation_and_evolution_of_the_Solar_System/cgElXHpM">Formation and evolution of the Solar System</a></li> <li><a href="/facts/Timeline_of_natural_history/7htqc31E">Timeline of natural history</a> (formation of the Earth to evolution of modern humans)</li> <li><a href="/facts/Timeline_of_the_far_future/0AYlHLon">Timeline of the far future</a></li> <li><a href="/facts/Timelines_of_world_history/UkXq5svT">Timelines of world history</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"Planck reveals an almost perfect universe". Max-Planck-Gesellschaft. 21 March 2013. Retrieved 17 November 2020. <a href="https://www.mpg.de/7044245/Planck_cmb_universe" target="_blank">https://www.mpg.de/7044245/Planck_cmb_universe</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Cheng, Ta-Pei; Li, Ling-Fong (1983). Gauge Theory of Elementary Particle Physics. Oxford University Press. p. 437. ISBN 0-19-851961-3. <a href="0-19-851961-3" target="_blank">0-19-851961-3</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Guth, "Phase transitions in the very early universe", in: Hawking, Gibbon, Siklos (eds.), The Very Early Universe (1985). <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Chow, Tai L. (2008). Gravity, black holes, and the very early universe: an introduction to general relativity and cosmology. New York: Springer. ISBN 978-0-387-73629-7. OCLC 166358163. <a href="978-0-387-73629-7" target="_blank">978-0-387-73629-7</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Peacock, J. A. (28 December 1998). Cosmological Physics (1 ed.). Cambridge University Press. doi:10.1017/cbo9780511804533. ISBN 978-0-521-41072-4. <a href="978-0-521-41072-4" target="_blank">978-0-521-41072-4</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Simion @Yonescat, Florin (6 April 2022). "Scientists have spotted the farthest galaxy ever". The Royal Astronomical Society. Retrieved 13 July 2023. <a href="https://ras.ac.uk/news-and-press/news/scientists-have-spotted-farthest-galaxy-ever" target="_blank">https://ras.ac.uk/news-and-press/news/scientists-have-spotted-farthest-galaxy-ever</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Wall, Mike (12 December 2012). "Ancient Galaxy May Be Most Distant Ever Seen". Space.com. Retrieved 12 December 2012. <a href="http://www.space.com/18879-hubble-most-distant-galaxy.html" target="_blank">http://www.space.com/18879-hubble-most-distant-galaxy.html</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Collaborative (11 April 2007). "Discovery of HE 1523–0901". Astrophysical Journal Letters. 660. CaltechAUTHORS: L117 – L120. Retrieved 19 February 2019. <a href="https://authors.library.caltech.edu/16647/" target="_blank">https://authors.library.caltech.edu/16647/</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>"GRB 090423 goes Supernova in a galaxy, far, far away". Zimbio. Archived from the original on 5 January 2013. Retrieved 23 February 2010. <a href="https://archive.today/20130105130128/http://www.zimbio.com/member/paulano123/articles/6044508/GRB+090423+goes+Supernova+galaxy+far+far+away" target="_blank">https://archive.today/20130105130128/http://www.zimbio.com/member/paulano123/articles/6044508/GRB+090423+goes+Supernova+galaxy+far+far+away</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Helmi, Amina (18 August 2020). "Streams, Substructures, and the Early History of the Milky Way". Annual Review of Astronomy and Astrophysics. 58 (1): 205–256. arXiv:2002.04340. Bibcode:2020ARA&A..58..205H. doi:10.1146/annurev-astro-032620-021917. ISSN 0066-4146. <a href="https://www.annualreviews.org/doi/10.1146/annurev-astro-032620-021917" target="_blank">https://www.annualreviews.org/doi/10.1146/annurev-astro-032620-021917</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Helmi, Amina (18 August 2020). "Streams, Substructures, and the Early History of the Milky Way". Annual Review of Astronomy and Astrophysics. 58 (1): 205–256. arXiv:2002.04340. Bibcode:2020ARA&A..58..205H. doi:10.1146/annurev-astro-032620-021917. ISSN 0066-4146. <a href="https://www.annualreviews.org/doi/10.1146/annurev-astro-032620-021917" target="_blank">https://www.annualreviews.org/doi/10.1146/annurev-astro-032620-021917</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Helmi, Amina (18 August 2020). "Streams, Substructures, and the Early History of the Milky Way". Annual Review of Astronomy and Astrophysics. 58 (1): 205–256. arXiv:2002.04340. Bibcode:2020ARA&A..58..205H. doi:10.1146/annurev-astro-032620-021917. 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