Page 25 - GALIET PHYSICS BLOSSOMS I+

(ii) Show how Jupiter appears to move in the sky as seen from the earth.
Motion of the Planets
All Planets show “retrograde + prograde motion”
Inner Planets
Mercury + Venus
Oscillate back and forth
Past the sun as it moves around the ecliptic
Outer Planets
Mars, Jupiter, Saturn
Oscillate back and forth Around the ecliptic
Brighteràretrograde phase ON PLANETARY MOTION
Planets generally traverse the celestial sphere from west to east, like the sun.
However, they seem to speed up and slow down during their travels, and at times, they appear to loop back and forth relative to the stars.21 In other words, there are times when the planets eastward motion (relative to the stars) stops, and the planet appears to move westward for a month or two before reversing direction again and continuing on its eastward journey.”22
Eastward motion = direct, or prograde, and
21 Chaisson, McMillan. Astronomy Today. 34. 22 Quoted from Astronomy Today. 35.
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