On November 12, here on Earth, it will be Mars’s New Year and mark the start of its 38th year since astronomers created a calendar for the planet. A Martian year is about 687 Earth days, and because a Martian day (a sol) is a little longer than our own (24 hours, 39 minutes), there are about 668 sols in a Martian year.
How it works: The Red Planet’s New Year coincides with its vernal equinox, a date that astronomers chose intentionally to start on April 11, 1955. Spring equinoxes, when the sun’s position in the sky crosses the planet’s celestial equator, are a nice, even way to track dates of celestial bodies, writes astronomer and columnist Phil Plait.
Who knew? Mars has four seasons like Earth, but they each last twice as long. Spring is particularly rough on the Red Planet–it’s the start of the dust season, and dust storms can grow to encompass the whole planet.
-Scientific American