A composite of Comet NEOWISE captured over Dizin, Iran, by Reyhaneh Valipour on 21 July 2020.īut every once in a while a planet will also appear to move in a retrograde direction. It’s generally only comets, with eccentric orbits, that travel around the Sun in a clockwise, or retrograde, direction. This is known as normal or direct motion. This is because all the planets, as viewed from above, orbit the Sun in an anticlockwise direction. If you look skywards at the same time of night on two different nights, you’ll notice that the planets have moved to the east. The planets normally move from west to east relative to the stars. The movement of the planets A composite showing star Betelgeuse's apparent movement across the sky. We call this apparent backwards movement 'retrograde motion'. But once in a while, if you observe the movements of the planets along the ecliptic, you might notice one suddenly appearing to stop, then begining to move backwards. The same can be said for the planets too. A composite image showing the apparent reversal of Mars's movement in the night sky. They just appear to be, from our perspective. The stars aren't really speeding across the sky. You can see them moving across the night sky in a matter of hours, but this is of course down to the fact that Earth is spinning while it orbits the Sun. But much of this is due to the apparent movement of the celestial sphere when seen from Earth. What is retrograde motion of the planets?Īs astronomers, we're used to watching objects move across the sky.
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