How many days are there in a mercury month?

Answer 1

It doesn't make sense to talk about a "Mercury month". Here on Earth, the month is defined by the Moon's revolution around Earth. At least, that's what the term "month" meant originally. There is no equivalent on Mercury, which has no moons. Of course, you could use any arbitrary time period and call it a "month", but there is no generally agreed-upon "month" for other planets, whether they have moons or not.