How many times does mercury rotate in a year?

Answer 1

Mercury rotates in about 58.65 Earth days.

Mercury's year: about 88 Earth days.

Earth's year: about 365 Earth days.

So Mercury rotates about 88/58.65 times in a Mercury year. That's about 1.55

times.

Mercury rotates about 365/58.65 times in an Earth year. That's about 6.22 times.

Answer 2

Mercury rotates once every 58.647 days, which is exactly 2/3 of its orbital period of 87.970 days, so it turns on its axis exactly 1 1/2 times during one of its years, causing the stars to move 1 1/2 times around the sky, each year. During that time, it moves once around the Sun, causing the Sun to appear to move backwards relative to the stars, one full turn. As a result, it has only half a day during one year (1 1/2 forward rotations by the stars, less 1 backward motion by the Sun), so that it takes two years (175.942 Earth days) for one day, three times as long as its rotation period. This seems very strange to us, but it is actually normal for a planet with a slow rotation to have a rotation period very different from its day length