Mont Blanc is a big mountain on Earth. But on the Moon, there is also a place called Mont Blanc. It's not really a mountain like the one on Earth, though. It's a big hole in the ground that was made by a big rock hitting the Moon a long time ago.
The Moon doesn't have air or water like Earth does, so things on the Moon don't change as much as they do on Earth. Mont Blanc has been there for a very long time and will probably stay there for a very long time, too.
People who study the Moon like to look at Mont Blanc and the other big holes on the Moon to learn about how things happen in space. It helps them understand more about the Moon and how it was made.