Does a Martian calendar need months, or other units between day and year?
There is no astronomical cycle on Mars that corresponds to our idea of a month. The moons of Mars are tiny in comparison to Earths Moon, and they are much closer to Mars than the Moon is to the Earth. Phobos orbits Mars three times per sol, and Deimos circles Mars in a little more than a sol. For this reason, a few Martian calendars have no months, but most include the month as a social cycle, as with the week. In human terms, it is useful to divide the year into smaller units.
