Mars rover Perseverance witnessed early this month that one of Mars’ moons – Phobos – passed in front of the sun. And that produces spectacular images!

A solar eclipse is always big news here on Earth. And it’s no different on Mars; Mars rover Perseverance was ready at the beginning of this month and recorded the complete eclipse – which, incidentally, only lasted a little more than 40 seconds.

solar eclipse

Where solar eclipses on Earth are the result of the moon crawling in front of the sun and blocking (part of) the sunlight, it is in fact no different on Mars. Only there it is not ‘our’ moon, but one of the two Martian moons that moves in front of the sun. At the beginning of April it was the turn of Phobos: the largest moon on Mars.

Special images

It is certainly not the first time that a Mars rover has captured a solar eclipse caused by Phobos; in 2004, on the basis of photos taken by the Mars rovers Spirit and Opportunity, a time lapse of a solar eclipse. And years later, Mars rover Curiosity even filmed a solar eclipse. Yet the images that Perseverance has now made are special. The Mars rover used its Mastcam-Z for this, a camera with which it can zoom in – unlike Curiosity, which also has such a Mastcam. And that’s what Perseverance did while capturing the eclipse. It results in the most zoomed-in images we have of a solar eclipse caused by Phobos. In addition, the frame rate – the number of images the camera takes per second – much higher. What also makes the images special is that they are in color. “It’s cool that you can see the eclipse exactly as the rover observed it from Mars,” said study researcher Mark Lemmon.

“I knew it (the images, ed.) would be good, but I didn’t expect it to be this great,” said Rachel Howson, part of the team responsible for running Perseverances Mastcam-Z. And that’s no exaggeration, see for yourself below!

What is immediately noticeable is that the shadow of Phobos – despite the bright sunlight – has been captured in quite detail by Perseverance. It is thanks to the fact that Perseverance’s Mastcam-Z is equipped with a sun filter that actually serves as a kind of sunglasses. “You can see details in the shape of Phobos’ shadow, such as ridges and mounds on the moon’s surface,” Lemmon said. And details are also visible on the sun itself. “You can also see sunspots.”

The images are not only spectacular, but also useful. This allows researchers to use the observations to get a better picture of Phobos’ orbit. In addition, researchers hope to learn more about Mars through Phobos; as Phobos orbits Mars, it exerts its gravity on Mars. Rocks in the crust and mantle of the planet are slightly deformed. By studying the changes Phobos is exerting on Mars through this gravitational effect, scientists can also better understand how pliable that crust and mantle are and draw conclusions about its composition based on that.

About Phobos
Phobos is a potato-shaped moon orbiting Mars. It is not the only moon that is rich in Mars: the moon Deimos also moves around Mars. Phobos is the largest moon on Mars. However, with a diameter of about 22 kilometers, Phobos is still 157 times smaller than our own moon. Phobos is much closer to Mars than the moon is to Earth; the distance between Mars and Phobos is about 6,000 kilometers, while the moon is more than 384,000 kilometers from the Earth’s surface. The distance between Phobos and Mars is also getting smaller and smaller. Phobos is expected to explode even on Mars in a few tens of millions of years.