Question

Describe how the motion of a planet (like Mars) among the stars of the zodiac on the sky is qualitatively different from the motion of an object like our Sun among the stars of the zodiac.

Answer 1

Explanation:

In the plane of the Solar System, called Ecliptic plane, Sun is at the center and all the planets including Earth are going around the Sun in their respective orbits. As seen form the Earth, Sun appear to go around it and in this process it  crosses through 12 constellations. These constellations are called as Zodiacs. Now since all the planets move in almost the same plane, they will appear in the sky to be lying near the ecliptic.

Sun's own motion is not that evident to us because of which the impact of that motion is nullified. But, motion of planet is clearly visible and it also shows in their annual round around the Sun. Here, Mars also shows retrograde motion which means it will show a back and forth motion in the sky. Because of which Mars might be visible in the same zodiac for a longer Duration as compared to the Sun.