How many days equals a year on Mercury?
A year on Mercury is 88 earth-days.
It sounds complex! It sort of is. Mercury revolves around the sun very quickly, but rotates around its own axis very, very slowly. One day on Mercury (sunrise to sunrise) is longer than one year on Mercury (one orbit around the Sun)! Mercurian Day: A day on Mercury equals 176 Earth days (from sunrise to sunrise, or the equivalent of a 24 hour day on Earth). It is daytime for one Mercurian year, and nighttime…
The length of a year (orbit) for Mercury is 88 Earth days, about 1/4 that of Earth. The planet spins 1.5 times during that period, about once every 58.7 Earth days. The combination of these motions results in a "solar day" (sunrise to sunrise) of 176 Earth days, or exactly twice as long as the year. So you could say that a Mercury year is only half of a Mercury solar day.