It takes only a glance at the Moon to realize that it has had a difficult time in its nearly 4.5-billion year history. But a new study shows that it has survived more asteroid impacts than its surface today.
New research suggests that the Moon's oldest impacts left almost invisible imprints due to their impact on a soft surface. This was the global ocean of magma, which covered the Moon in its youth and solidified it.
These soft landings that left little evidence of any event could be the reason why the Moon's current appearance doesn't correspond with what scientists believe it did in the first billion years.
Katarina Miljkovic, a Curtin University planetary scientist, says that these large impact craters (often referred to by impact basins) formed during the lunar magma oil solidification over four billion years ago. They should have produced craters with a different appearance than those created later in geologic time.
Although the idea of a global Magma Ocean on the Moon is not new, the research tries to link it with the information we have about the Solar System at that time.
Multiple clues exist as to what has happened to the Moon's formation, including Solar System modeling and evidence of impact shocks within rocks that Apollo astronauts have actually recovered from the surface.
There are some studies that suggest the magma boiling lakes could have survived for up to 200 million years. This latest research also shows how this would match the dates for the bombardment of large asteroids.
Miljkovic says that although the timeframe for solidification of lunar magma ocean differs between studies, it could have been extended enough to experience the large impact bombardment history common for the early periods of Solar System evolution.
"As the Moon ages and the surface cools, it becomes more difficult, and the bombardment imprints become much more visible by remote sensing."
This information is crucial in understanding how the Solar System got to be what it is.
Even though we know there is an unknown, such as how many asteroid impacts could have been missed in previous lunar cratering records assessments, it helps us improve our models of what happened billions of years ago.
Because we are so close to the Moon, any event that happens to it would have an effect on Earth. This gives us a better understanding about how the planet and its inhabitants came to be.
Miljkovic says, "Translating these findings will help future research understand how the early Earth experienced impact and how it would affect our planet's evolution."
Nature Communications published the research.
