Question

What is the sidereal orbit for Venus and what is its synodic period? Explain why is there a difference. Why is the synodic period for Neptune very close to the length of the Earth year?

Answer 1

Venus sidereal orbit = 0.615 year
Venus synodic = 584 days
It makes sense that Venus takes less time to orbit the Sun with respect to the stars that does the Earth. The synodic period represents the time it takes Venus to move from two successive identical configurations as viewed from the Earth, which is also orbiting the Sun. This causes the difference in days.
The synodic period for Neptune is close to the length of an Earth year because relative to the time it takes Earth to orbit the Sun, Neptune moves only a small distance along its orbital path.