- Mercury is the closest planet to the Sun. Its average distance from the Sun is about 57.9 million kilometers, which is approximately 5.8 crore km. - Mercury has the shortest orbital period of all the planets, taking only about 88 Earth days to complete one revolution around the Sun. - The other options list incorrect planets or distances/periods: Venus is ~108 million km, 225 days; Mars is ~228 million km, 687 days; Saturn is ~1.4 billion km, ~29.5 years.