How Long is a Year on Mars?
Written by Fraser Cain
A year on Mars lasts 687 Earth days. In other words, a Martian year is almost double an Earth year. When you celebrate your 25th birthday on Mars, you'd actually be 47 years old if you'd been living on Earth.
As with all the planets in the Solar System, Mars takes an elliptical journey around the Sun. This eccentricity in the Martian orbit brings it as close as 207 million km to the Sun, at one point in its orbit, and then 250 million km at the most distant point.
The planet has an axial tilt of 25.19 degrees; very similar to the tilt of the Earth's axis.
Because of the tilt, Mars has seasons like Earth, with very similar changes to its ice caps and weather systems. But because of the eccentricity of its orbit, the seasons aren't the same length. Spring in the northern hemisphere lasts 194 Martian days (sols), while autumn is only 142 days long.
Since a year on Mars is roughly twice a year on Earth, the two planets only get close to once another every two years or so. This is the launch window NASA uses to send spacecraft to Mars. That's why there are a flurry of missions every two years, with a break in between. It's also why only becomes really bright in the sky every two years.
NASA's Mars rovers have been working so long, they were hired on for a third year. Here's an example of when Mars is at its closest approach.
All you ever wanted to know about Martian time. Information from NASA about Spirit celebrating 1 year on Mars.
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
