Martian days are moving faster than they used to, and no one knows why

The New York Times reports that time has been inexplicably contracting on red terrestrial neighbor. Based on recent data from NASA's InSight lander, the days on Mars seem to be getting shorter. Researchers have factored in the Doppler effect that distorts the wavelength frequencies as the two planets move, but they still can't account for the discrepancy.

From the article:

Once the scientists accounted for all of that, there were leftover frequency variations. Mars, because it is not a perfectly round sphere, wobbles like a top. "The primary goal is to measure the rotation," said Sébastien Le Maistre of the Royal Observatory of Belgium, who led the radio science experiment, known as the Rotation and Interior Structure Experiment, or RISE.


When including the Viking mission's Doppler measurements from 47 years ago, the scientists found a slight speeding up in the spin of Mars, which has led to a shortening of a Martian day by about 1.5 millionths of a second per Martian year. (A Martian year is almost twice as long as a year on Earth.)

"It was a surprise," Dr. Banerdt said. "We did not expect to see that at all."

That is the opposite of Earth, where the moon is slowly moving farther away and the length of the day is getting longer, the main reason that leap seconds are occasionally added to timekeeping (although that will change in 2035). The melting of glaciers and shifting atmosphere can also change the spin rate.

It's some weirdly fascinating physics, only some of which I can grasp—as the rest of my brain power is occupied with a downward spiral into cosmic horror.

Days on Mars Are Getting Shorter [Kenneth Chang / The New York Times]

Full disclosure: I also write for Wirecutter, which is owned by the New York Times Company, which publishes The New York Times]