Those of us still humming on back-to-school energy can add some Red Planet flavor: We just marked the beginning of a new year on Mars.
The Martian new year officially clicked over today (Sept. 30) at 4:16 a.m. EDT (0816 GMT), when the Red Planet once again began its nearly 687-Earth-day journey around the sun.
But if you're a Martian, you wouldn't use Earth days. A Mars day, or "sol," lasts 24 hours and 39 minutes — the time it takes the Red Planet to rotate once. There are 668 sols in a Martian year.
Sept. 30 as New Year's Day on Mars is something of a human construct: Astronomers chose it because Sept. 30 marks the northern equinox, when spring begins in Mars' north and autumn starts in the south.
"Like Earth, Mars has four seasons — winter, spring, summer and autumn," officials with the European Space Agency (ESA) stated in a post about the Martian new year.
"Unlike Earth's seasons, Martian seasons are not of equal lengths due to Mars' more elliptical orbit," they added. "The planet's axial tilt causes the northern hemisphere to receive more sunlight during the northern summer, and the southern hemisphere to receive more sunlight in northern winter."
The strange seasons on Mars also bring a consequence: dust. In the back half of the long Martian year, the Red Planet gets closer to the sun and sees its atmosphere warm up. The warmth brings dust, as winds loft particles from the regolith on the surface.
"Once airborne, these brownish particles heat up and redistribute some of that warmth to the surrounding atmosphere. This process can rapidly pump a lot of dust," ESA stated.
Daily conditions on Mars are also tough, no matter the season. At noon in summer, for example, temperatures range between 32 degrees and 140 degrees Fahrenheit (0 and 60 degrees Celsius), but winter sees the mercury plunge to as low as minus 166 degrees F (minus 110 degrees C).
You can check out the conditions on Mars up close, by following along with NASA's Perseverance and Curiosity rovers. These six-wheeled robots send back images nearly daily, and the agency generally provides a few updates about their activities each month.
