A day on Mars is about 37 minutes longer than a day on Earth, but both planets seem to be trying to make up for that difference. Data from NASA’s InSight rover revealed that the days on Mars are getting shorter and shorter. Scientists aren’t entirely sure why the days on Mars are getting shorter.
The days are getting shorter on Mars
InSight, a robotic lander designed to probe the deep interior of the planet Mars, continued its work from 2018 until its solar panels were covered with dust and became inoperable in December 2022. InSight’s original purpose was to probe the interior of the Red Planet, but it also houses a pair of radio antennas that could help measure the rotation of Mars.
These antennas were designed to be installed with NASA’s Deep Space Network on Earth. Thanks to the lengthening and shortening of the radio waves constantly sent to the Earth, the behavior of Mars would be measured. We call this the Doppler effect. We actually experience the Doppler effect every day: For example, the sound of an ambulance becomes quieter as it gets farther away and higher as it gets closer.
Moving on, scientists analyzed the data InSight collected over 900 Martian days and made adjustments to take into account other factors such as solar wind and moisture in Earth’s atmosphere. In this way, scientists were able to look for variations that could be attributed entirely to changes in the rotational speed of Mars. Despite the corrections, of course, the process is not easy because it was aimed to detect the changes of a few tens of centimeters that Mars had made over the course of a year.
Analyzing the accumulated data, it was determined that the rotation of Mars is accelerating, albeit by a very small amount, on an annual basis: 4 milliseconds, or 0.004 seconds. This shortens the 24.6-hour day on Mars by a few fractions of a millisecond each year, according to NASA.
Exactly why the planet is accelerating is currently unknown. Our Moon plays an important role in Earth’s rotational speed and actually makes our days a little longer. But Mars’ two moons are much smaller and are not thought to have such an effect. Instead, scientists speculate that the ice accumulating at the poles could be caused by mass change or by landmasses that reappear after being covered by glaciers. You can watch the method used to measure the changing rotation speed in the video below.
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