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Celestial mechanics

Orbital mechanics

Accretion (astrophysics)

Accumulation of particles into a massive object by gravitationally attracting more matter

Time of the day between noon and evening

Either of two extreme points in a celestial object's orbit

Astronomical transit

Term in astronomy

Axial precession

Gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis

Barycenter (astronomy)

Center of mass of multiple bodies orbiting each other

Atmospheric phenomenon

Bi-elliptic transfer

Maneuver that moves a spacecraft from one orbit to another

Period of twilight in the morning or evening

Celestial mechanics

Branch of astronomy

Co-orbital configuration

Configuration of two or more astronomical objects

Time that marks the beginning of the twilight before sunrise

Combination of all direct and indirect sunlight outdoors during the daytime

Daytime Protocol

Computer text protocol for viewing clock time

Darkest stage of twilight, at end of astronomical twilight after sunset and just before night

Astronomical event where one body is hidden by another

Intervals of eclipses

Escape velocity

Concept in celestial mechanics

Period of the day between afternoon and nighttime

Orbit for an artificial satellite in which natural drifting due to the central body's shape has been minimized by careful selection of the orbital parameters

Lunar phase: completely illuminated disc

Geostationary orbit

Circular orbit above the Earth's equator and following the direction of the Earth's rotation

Geosynchronous orbit

Orbit keeping the satellite at a fixed longitude above the equator

Golden hour (photography)

First and last hour of sunlight during the day

Graveyard orbit

Supersynchronous orbit where spacecraft are intentionally placed at the end of their operational life

Gravitational collapse

Contraction of an astronomical object due to the influence of its own gravity

Space navigation technique

Periodic, three-dimensional orbit

Hohmann transfer orbit

Elliptical orbit used to transfer between two orbits of different altitudes, in the same plane

Horseshoe orbit

Type of co-orbital motion of a small orbiting body relative to a larger orbiting body

Kepler's laws of planetary motion

Scientific laws describing motion of planets around the Sun

One of five positions in an orbital configuration of two large bodies where a small object can maintain a stable relative position

Apparent oscillation of a minor body seen from the major body it orbits

Lissajous orbit

Quasi-periodic orbital trajectory

Low Earth orbit

Orbit around Earth with an altitude between 160 and 2,000 kilometers

Natural phenomenon wherein the Earth casts a shadow on the Moon

The shape of the Moon's directly sunlit portion as viewed from Earth

Transition time from one day to the next

Natural phenomenon when daylight lasts for a whole day

Type of high-latitude satellite orbit

Period of time from midnight or sunrise to noon

Period of time from midnight or sunrise to noon

Phase of the Moon

Period of darkness

12 o'clock in the daytime

Maneuver in which a spacecraft falls into a gravitational well, and then accelerates when its fall reaches maximum speed

Orbital eccentricity

Amount by which an orbit deviates from a perfect circle

Orbital elements

Parameters that uniquely identify a specific orbit

Orbital inclination

Angle between a reference plane and the plane of an orbit

Orbital mechanics

Field of classical mechanics concerned with the motion of spacecraft

Orbital resonance

Regular and periodic mutual gravitational influence of orbiting bodies

Orbital station-keeping

Maneuvers made to maintain a particular orbit

Natural phenomenon when the night lasts for more than 24 hours, occurring only inside the polar circles

Satellite orbit with high inclination

Astronomical concept

Saros (astronomy)

Series of eclipses separated by a saros period

Timekeeping system

Natural phenomenon wherein the Sun is obscured by the Moon

Space rendezvous

A series of orbital maneuvers to bring two spacecraft into the vicinity of each other

Sunrise (disambiguation)

Topics referred to by the same term

Daily falling of the Sun below the horizon

Sun-synchronous orbit

Type of geocentric orbit

Full or new moon which appears larger due to coinciding with perigee

Terminator (solar)

Moving line that separates the illuminated day side and the dark night side of a planetary body

Tidal acceleration

Cause of tidal locking

Situation in which an astronomical object's orbital period matches its rotational period

Transit of Mercury

A transit of Mercury across the Sun

Transit of Venus

Astronomical transit of Venus across the Sun

Illumination of atmosphere when the Sun is not directly visible because it is below horizon

Umbra, penumbra and antumbra

Distinct parts of a shadow

Velocity dispersion

In astronomy, the statistical dispersion of velocities about the mean velocity for a cluster of stars or galaxies

Faint solar glow caused by interplanetary dust at sunset and sunrise