Retrograde motion occurs as the Earth moves around the sun and the stellar views at night change little by little. The orbit, in turn, makes objects like planets in our solar system move horizontally across the sky throughout the year.
All the outer planets of the solar system are affected by retrograde motion periodically before they reach opposition.
Uranus can be seen in the night sky with the naked eye, but retrograde motion requires a telescope or binoculars.
The ice giant will enter retrograde motion beginning at 9:40 p.m. EDT Wednesday and will remain in the motion until Jan. 22.
Astronomers advise skywatchers to look to the southeast between 10:46 p.m. and 5 a.m. when Uranus is above the horizon before dawn. Watchers can also use the stars in the constellation Aries to spot the blue-green planet.
"Uranus will be sitting at the bottom corner of a box formed by the 4th and 5th magnitude stars Botein or Delta Arietis, Epsilon Arietis, and Pi Arietis -- creating a distinctive asterism for anyone viewing Uranus," geophysicist Chris Vaughan said according to Space.com.
Centuries ago, the backward motion puzzled ancient observers because they couldn't explain why the planets shifted in the sky during the year when, they believed, they were in uniform circular orbits around the Earth.
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