Why is a year on Earth 365 days?
Show answer & explanation
Answer: Time for Earth to orbit sun
Time for Earth to orbit sun ✓ — Correct! A year is defined by Earth's orbital period—time to complete one revolution around the sun. Earth orbits at ~30 km/s, covering ~940 million km. Orbital period depends on distance and sun's mass (Kepler's Third Law). Actually 365.25 days—why we need leap years every 4 years! Other planets have different year lengths: Mercury ~88 days, Mars ~687 days, Jupiter ~12 Earth years!
Earth's rotation speed — Wrong. Rotation determines day length (~24 hours), not year length. Year is defined by orbital revolution around the sun.
Distance from the sun — Wrong. Distance affects orbital period (Kepler's laws), but 365 days is specifically how long Earth takes to orbit at its current distance.
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