How Long is a Day on Mars?
Written by Fraser Cain
A day on Mars is 24 hours, 39 minutes and 35 seconds; amazingly similar to a day on Earth. In fact, this is just one of the reasons that space enthusiasts think that Mars might make a good planet for colonization. With a length of day that's so similar, Earth plants and animals might adapt to the Martian day quite easily.
Of course, the Martian day does have that extra 39 minutes and 35 seconds over an Earth day. During the early days of NASA's Spirit and Opportunity missions to Mars, NASA engineers wore two watches; one with Earth time, and another with Mars time. Each day, their schedule would slip back 40 minutes, and eventually they were working through the Martian day, even if that was in the middle of the night here on Earth.
Once they had worked with the rovers for several months, the engineers went back to working regular days, sometimes interacting with the rovers in the Martian day, and other times during the Martian night.
Just like Earth, Mars has sidereal days and solar days. A sidereal day is the length of time Mars takes to complete one rotation on its axis compared to the background stars. A sidereal day on Mars is 24 hours, 37 minutes, and 22 seconds. A solar day is the length of time it takes for the Sun to return to the meridian. Because Mars is orbiting around the Sun, this position moves a little bit every day. The solar day is 24 hours, 39 minutes and 35 seconds.
A Martian day is about 2.7% longer than Earth's.
Want more information? Learn about living on Mars time. NASA has a great clock for calculating Mars time.
Finally, if you'd like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.
Filed under: Astronomy
