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The retrograde motion of a hypothetical extremely distant (and nearly non-moving) planet would take place during a half-year, with the planet's apparent yearly motion being reduced to a parallax ellipse. The center of the retrograde motion occurs at the planet's opposition which is when the planet is exactly opposite the Sun.
in apparent retrograde motion [2] visible almost all night – rising around sunset, culminating around midnight, and setting around sunrise [3] at the point in its orbit where it is roughly closest to Earth, making it appear larger and brighter [4] nearly completely sunlit; the planet shows a full phase, analogous to a full moon [5]
Many associated the classical planets (these star-like points visible with the naked eye) with deities, in part due to their puzzling forward and retrograde motion against the otherwise fixed stars, which gave them their nickname of "wanderer stars", πλάνητες ἀστέρες (planētes asteres) in Ancient Greek, from which today's word ...
Retrograde motion is an apparent change in the movement of a planet in the sky, but that doesn’t mean the planet is physically moving backward in its orbit. ... Key Dates: Mercury retrograde ...
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). It may also describe other motions such as precession or nutation of an object's rotational axis .
A satellite with an orbital inclination between 90° and 180° (or, equivalently, between 0° and −90°) is said to be in a retrograde orbit. [note 2] A satellite in a direct orbit with an orbital period less than one day will tend to move from west to east along its ground track. This is called "apparent direct" motion.
At perihelion, Mercury's orbital angular velocity slightly exceeds the rotational velocity, making the Sun appear to go retrograde. Four days after perihelion, the Sun's normal apparent motion resumes. From the moment the top of the Sun can be seen to the moment someone can see a full circle, a sunrise would take almost 6 hours. [2]
Retrograde motion of Mars as viewed from the Earth. Figure 3: Planets revolving the Sun follow elliptical (oval) orbits that rotate gradually over time (apsidal precession). The eccentricity of this ellipse is exaggerated for visualization. Most orbits in the Solar System have a much smaller eccentricity, making them nearly circular.