General Knowledge
Why do we get an afternoon on Mars that is only slightly longer than ours?
- A Martian day is about 24 hours 37 minutes
- Mars spins twice as fast
- Mars does not spin
The answer is A Martian day is about 24 hours 37 minutes. A sol is 24 hours 37 minutes - oddly close to Earth's day.
Because a Martian day - a sol - is 24 hours and about 37 minutes, which is a coincidence with no particular reason behind it. The two planets formed from the same disc but their spin rates come from the chaos of what hit them, and Venus, formed nearby, takes 243 days to turn once and does it backwards.
It makes Mars unusually comfortable to work with and quietly miserable to work on. Rover teams on Earth run on Mars time during a mission, shifting their working day forward by 37 minutes daily, so within a fortnight they are starting work in the middle of the night; families report it feeling like permanent jet lag. Some teams issue special watches.
Mars also has a comparable axial tilt, about 25 degrees against Earth's 23.5, so it has recognisable seasons - twice as long, since the year is 687 days. What it does not have is a large moon to stabilise that tilt, so over millions of years it wanders far more than Earth's does, which has swung the Martian climate around dramatically.