How Many Days In A Year On Jupiter In Days. How long a day and year on earth. Jupiter is the fastest spinning planet in our solar system, rotating on average once in just under 10 hours.
Jupiter’s axis is tilted at only 3 degrees (like venus). This rapidly spinning gas giant completes a day in 10 hours but due to its orbital period a jupiter year lasts about 12 earth years or to be exact 4,333 earth days.