Darkness might not be quite the right word.

Astronomically, the spectacle in the Martian sky that the camera of the new American Mars rover "Perseverance" filmed on April 2nd and that Nasa has now published is a so-called transit: the passing of another celestial body in front of a star or the sun.

It didn't really get dark.

Because while our moon, seen from Earth, happens to appear exactly as large as the sun's disk and is almost as circular, so that it can cover it completely during a transit, neither of these is the case with the Martian moon Phobos.

Not only is it 157 times smaller than Earth's Moon and orbiting 36 times closer to Mars than Earth's, it's not a sphere, but rather potato-shaped, measuring 27 by 22 by 18 kilometers.

Ulf von Rauchhaupt

Editor in the “Science” section of the Frankfurter Allgemeine Sunday newspaper.

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Nevertheless, the video of the event, which lasts just 40 seconds, is spectacular, because Phobos appears smaller, but not much smaller than the sun's disk, as would be the case for a transit of Mercury, Venus or Earth.

In addition, the outlines of the satellite created by structures on the lunar surface can be seen, which is probably an asteroid that got into the orbit of Mars at some point.

Now a Phobos transit has been filmed in unprecedented resolution and in color for the first time.

As early as March 2004, the Perseverence predecessor "Opportunity" photographed the mini moon in front of the sun for the first time.

And its still active predecessor "Curiosity" shot the first, somewhat choppy film of such a process in August 2013.

Mars has a second, smaller, but also potato-shaped companion called Deimos, orbiting at a greater distance.

Phobos and Deimos (Greek for "fear" and "dread") are named after the two companions of the god of war Ares, whom the Romans identified with their god Mars.

Passings of Deimos in front of the sun have also been observed - first in March 2004 by "Opportunity" and by its sister craft operating on the other side of the planet "Spirit".

The quality of the new film demonstrates the advances in Mars rovers' camera technology;

Technology, which of course was not primarily given to them for such observations of the sky.

Nevertheless, these are also of scientific interest, as their detailed analyzes provide additional data on how Mars pulls on its two small moons, which then helps to shed light on the internal structure of the red planet.

At least the orbit of Phobos, which is only 6000 kilometers high, is unstable in the long term.

In a few tens of millions of years it will crash onto the surface of Mars.

Will Elon Musk take this into account when choosing a location for his Mars colony?

But as long as Phobos remains in the Martian sky, its transits would not be such a rare spectacle for the colonists - at least much more frequently than those of the three inner planets seen from Mars.

As the only planetary transit to date from there – or from the surface of any celestial body beyond Earth – “Curiosity” succeeded in observing a transit of Mercury in June 2014.

Earth will next pass in front of the Sun on November 10, 2084 as seen from Mars.

Perhaps people will not only follow this through robotic eyes.