How deep are moon craters

Geology of the moon Crust, crater & the moon face

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There is a lot going on under the gray, crater-strewn surface of the moon covered with thick moondust: our satellite is not a dead lump of rock. Moonquakes rumble and its crust is still a mystery today.

Status: January 17, 2019

Tens of thousands of craters on its surface testify to the bombardment to which our moon is constantly exposed. The largest crater measures more than 2,000 kilometers, the smallest you have to look for with a magnifying glass.

Moons are mostly "dead" celestial bodies: They are so small that they have long since cooled down, with no activity inside them. The planets are completely different: the large gas planets are still so active that they - to a lesser extent - even shine themselves. And here earthquakes and erupting volcanoes testify to the activity under the crust of our planet.

There are of course exceptional moons like Jupiter's Io with active volcanism. Conversely, not all planets are so lively: Mercury, for example, is presumably completely hardened due to its proximity to the sun. The smallest moons are trapped asteroids - simple rocks that have never been geologically active.

Deep-layered and with a hard core

Look inside the moon

Our big moon has more to offer: it is no longer active, but its structure is complex: it has a thick crust, much thicker than that of the earth. On the side facing us, the lunar crust is around seventy kilometers thick, while on the side facing away from the earth, it is 150 kilometers thick. Why has not yet been clarified. Under the crust there is a mantle of basalt rocks similar to that of the earth. However, while parts of the mantle on our planet have melted and emerge as magma during volcanic eruptions, the interior of the moon has probably now completely hardened. At its core, astronomers suspect that the moon also has an iron core with a radius of 100 to 400 kilometers.

Beat by the earth

The surface of the moon

However, the cooled-down lunar body is not quite as calm: since the Apollo missions left seismometers on the moon, we have known that it is constantly shaken - with a strength of up to 5.5 on the Richter scale. Sunrise and sunset alone cause slight shudders in its crust, which heats up and cools down considerably. After all, day and night on the moon each last two weeks.

Our companion also vibrates every time a meteorite hits him.

Our earth also moves the moon at its core, at depths up to a thousand kilometers below the crust: the tidal force of our planet literally beats the moon through.

The moon is bombarded by meteorites. Craters and Dust ...

By the way, our silvery moon is not that bright: The albedo, its reflectivity, is only 0.12, so it only reflects 12 percent of the incident light - less than asphalt. No wonder, because it is covered in meter-thick moondust, the so-called regolith. This is caused by the permanent bombardment by meteorites, in which moon rocks are literally pulverized.

The evaluation of over 14,000 image pairs from the Lunar Reconnaissance Orbiter (LRO) space probe has shown that 180 new craters with a diameter of more than ten meters are created on the moon's surface every year - and thus significantly more than researchers had assumed.

Looked deep into the craters

180 new lunar craters per year NASA's lunar probe Lunar Reconnaissance Orbiter (LRO) has been scrutinizing the moon since 2009. Again and again she photographs the same places on the moon. So you have comparison images at a time. When evaluating over 14,000 such pairs of images, the researchers at Arizona State University calculated that the moon is hit by a meteorite around 180 times a year, forming craters of more than ten meters, as shown in the photo. This lunar crater was created between October 2012 and April 2013.

The face of the moon - seas of magma

The familiar face of the moon is created by the "Maria", lava basins on the moon.

Large, dark areas cover a third of the lunar surface facing us and form the typical lunar face. They are the so-called Maria: low plains with a lava floor.

They probably arose in the early days of the moon, when its crust was still soft and its interior was still liquid.

Large meteorites were able to penetrate the crust, so that liquid magma oozed out and filled the crater flat: a "mare" was created - named after the sea it was previously thought to be.

By the way, on the far side of the moon there is almost no Maria. The reason for this could be that the lunar crust there is more than twice as thick and could not be penetrated as easily.

There is actually no atmosphere on the moon. There are traces of hydrogen, helium, neon and argon. They are particles of the solar wind, attracted by the lunar mass, or gases emerging from the lunar rock, but in vanishingly small quantities. While the air pressure on earth at sea level is normally one bar, the pressure on the moon is not even a billiardth of a bar. A fact that the Apollo 15 lunar mission used for historical evidence, as the film on the left shows.