Retrograde and prograde motion

retrogradeprograderetrograde orbitretrograde motionprograde orbitretrograde rotationprograde motionopposite directionopposite directionsretrograde direction
Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object (right figure).wikipedia
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Venus

Morning Starevening starplanet Venus
The rotations of most planets, except Venus and Uranus, are also prograde.
With a rotation period of 243 Earth days, it takes longer to rotate about its axis than any planet in the Solar System and goes in the opposite direction to all but Uranus (meaning the Sun rises in the west and sets in the east).

Triton (moon)

TritonAndvari Triton
Retrograde satellites are generally small and distant from their planets, except Neptune's satellite Triton, which is large and close.
It is the only large moon in the Solar System with a retrograde orbit, an orbit in the direction opposite to its planet's rotation.

Solar System

outer Solar Systeminner Solar Systemouter planets
In our Solar System, the orbits about the Sun of all planets and most other objects, except many comets, are prograde, i.e. in the same direction as the Sun rotates.
There are exceptions, such as Halley's Comet.

Natural satellite

moonmoonssatellite
Most natural satellites have prograde orbits about their planets.
The natural satellites orbiting relatively close to the planet on prograde, uninclined circular orbits (regular satellites) are generally thought to have been formed out of the same collapsing region of the protoplanetary disk that created its primary.

Orbit

orbitsorbital motionplanetary motion
Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object (right figure).
A prograde or retrograde impulse (i.e. an impulse applied along the orbital motion) changes both the eccentricity and the orbital period.

Orbital inclination

inclinationinclinedtilted
A celestial object's inclination indicates whether the object's orbit is prograde or retrograde.

Hot Jupiter

hot JupitersPuffy planetultra-short period planet
In 2010 the discovery of several hot Jupiters with backward orbits called into question the theories about the formation of planetary systems.
It has been found that several hot Jupiters have retrograde orbits and this calls into question the theories about the formation of planetary systems, although rather than a planet's orbit having been disturbed, it may be that the star itself flipped over early in their system's formation due to interactions between the star's magnetic field and the planet-forming disc.

Planet

planetsFormer classification of planetsplanemo
In our Solar System, the orbits about the Sun of all planets and most other objects, except many comets, are prograde, i.e. in the same direction as the Sun rotates.
In Arabic, Mercury is عُطَارِد (ʿUṭārid, cognate with Ishtar / Astarte), Venus is الزهرة (az-Zuhara, "the bright one", an epithet of the goddess Al-'Uzzá ), Earth is الأرض (al-ʾArḍ, from the same root as eretz), Mars is اَلْمِرِّيخ (al-Mirrīkh, meaning "featherless arrow" due to its retrograde motion ), Jupiter is المشتري (al-Muštarī, "the reliable one", from Akkadian ) and Saturn is زُحَل (Zuḥal, "withdrawer" ).

Irregular moon

irregular satelliteirregularirregular satellites
Retrograde satellites are generally small and distant from their planets, except Neptune's satellite Triton, which is large and close.
In astronomy, an irregular moon, irregular satellite or irregular natural satellite is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit.

Regular moon

regular satelliteregular satellitesregular
Nearly all regular satellites are tidally locked and thus have prograde rotation.
In astronomy, a regular moon is a natural satellite following a relatively close and prograde orbit with little orbital inclination or eccentricity.

Tidal acceleration

tidal frictiontidal decelerationtidal heating
All retrograde satellites experience tidal deceleration to some degree.
The acceleration causes a gradual recession of a satellite in a prograde orbit away from the primary, and a corresponding slowdown of the primary's rotation.

Atmosphere of Venus

atmosphereVenusian atmosphereVenus
Venus is close enough to the Sun to experience significant gravitational tidal dissipation, and also has a thick enough atmosphere to create thermally driven atmospheric tides that create a retrograde torque.
The thick troposphere also makes the difference in temperature between the day and night side small, even though the slow retrograde rotation of the planet causes a single solar day to last 116.5 Earth days.

Rings of Saturn

Cassini DivisionA Ringrings
The particles in Saturn's Phoebe ring are thought to have a retrograde orbit because they originate from the irregular moon Phoebe.
Well beyond the main rings is the Phoebe ring, which is presumed to originate from Phoebe and thus to share its retrograde orbital motion.

Neptune

NeptunianAtmosphere of NeptuneNeptune-mass
Retrograde satellites are generally small and distant from their planets, except Neptune's satellite Triton, which is large and close.
Unlike all other large planetary moons in the Solar System, Triton has a retrograde orbit, indicating that it was captured rather than forming in place; it was probably once a dwarf planet in the Kuiper belt.

Orbital resonance

1:1 resonanceresonancemean-motion resonance
Most known objects that are in orbital resonance are orbiting in the same direction as the objects they are in resonance with, however a few retrograde asteroids have been found in resonance with Jupiter and Saturn.
Most bodies that are in resonance orbit in the same direction; however, the retrograde asteroid 514107 Kaʻepaokaʻawela appears to be in a stable (for a period of at least a million years) 1:−1 resonance with Jupiter.

Uranus

Uranian34 TauriMagnetosphere of Uranus
The rotations of most planets, except Venus and Uranus, are also prograde.

Orbital pole

ecliptic polenorth ecliptic poleecliptic north pole
As of 2012, data is available for less than 200 asteroids and the different methods of determining the orientation of poles often result in large discrepancies.
If the fingers of the right hand are curved along the direction of orbital motion, with the thumb extended and oriented to be parallel to the orbital axis, then the direction the thumb points is defined to be the orbital north.

Phoebe (moon)

PhoebeA moonSaturn IX (Phoebe)
The particles in Saturn's Phoebe ring are thought to have a retrograde orbit because they originate from the irregular moon Phoebe.
Phoebe's orbit is retrograde; that is, it orbits Saturn opposite to Saturn's rotation.

Meteoroid

meteormeteorsfireball
Meteoroids in a retrograde orbit around the Sun hit the Earth with a faster relative speed than prograde meteoroids and tend to burn up in the atmosphere and are more likely to hit the side of the Earth facing away from the Sun (i.e. at night) whereas the prograde meteoroids have slower closing speeds and more often land as meteorites and tend to hit the Sun-facing side of the Earth.
Earth travels at about, so when meteoroids meet the atmosphere head-on (which only occurs when meteors are in a retrograde orbit such as the Eta Aquariids, which are associated with the retrograde Halley's Comet) the combined speed may reach about (see Specific energy#Astrodynamics).

Kozai mechanism

Kozai resonanceKozai-Lidov mechanismKozai instability
Retrograde motion may also result from gravitational interactions with other celestial bodies in the same system (See Kozai mechanism) or a near-collision with another planet, or it may be that the star itself flipped over early in their system's formation due to interactions between the star's magnetic field and the planet-forming disk.
It can drive an initially near-circular orbit to arbitrarily high eccentricity, and flip an initially moderately inclined orbit between a prograde and a retrograde motion.

(471325) 2011 KT19

2011 KT19(471325) 2011 KT 19 (471325) 2011 KT 19 ("Niku")
. Other Kuiper belt objects with retrograde orbits are (471325) 2011 KT 19,, and 2011 MM 4.
(nicknamed Niku; ) is a trans-Neptunian object that has an unusual 110° tilted solar orbital plane and retrograde orbit around the Sun.

WASP-17b

about twice as large as Jupiterb
WASP-17b was the first exoplanet that was discovered to be orbiting its star opposite to the direction the star is rotating.
It is the first planet discovered to have a retrograde orbit, meaning it orbits in a direction counter to the rotation of its host star.

Halley's Comet

Comet Halley1P/HalleyHalley
Halley's Comet has a retrograde orbit around the Sun.
Unusual for an object 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.

List of exceptional asteroids

second-largestList of notable asteroidsfourth-largest asteroid
Only a few dozen asteroids in retrograde orbits are known.
Minor planets with orbital inclinations greater than 90° (the greatest possible is 180°) orbit in a retrograde direction.

Hill sphere

Hill radiusRoche sphereHill
Within the Hill sphere, the region of stability for retrograde orbits at a large distance from the primary is larger than that for prograde orbits.
The region of stability for retrograde orbits at a large distance from the primary, is larger than the region for prograde orbits at a large distance from the primary.