The length of year on Mars is 686.980 Earth days. In other words, every time Mars orbits the Sun once, Earth has experienced almost 687 days, or 1.88 years.
If you’d like to calculate your age on Mars, just divide your current age by 1.88. For example, if you’re 15 now, divide by 1.88 and you’ll get 7.98 in Mars years.
The Mars length of year is almost twice the length of time for a year on Earth, and so all of the seasons on Mars are doubled. Summer takes twice as long and so does Winter. Mars and Earth make their closest approach to each other every 26 months. When Mars is at its closest point, astronomers say that Mars is in opposition. At this point, Mars is only 55.7 million km from Earth. Because the Mars opposition occurs every 2 years, NASA scientists schedule rocket launches to Mars during each one of these close approaches. This provides a flight path that uses up the minimum amount of fuel to reach Mars in a short amount of time.
We’ve also recorded an episode of Astronomy Cast all about Mars. Listen here, Episode 52: Mars.