It's called Apollodorus. A crater with hundreds of cracks.
The problem is, those cracks aren't made by the crater!
Back in 2008. The Messenger spacecraft zipped past Mercury. Snapped pictures of its side we had never seen before, and found many interesting things.
When scientists saw this weird, many-legged crater, they nicknamed it “The spider 🕷️”.
But something was off..
Those cracks turned out to be older than the crater. How do we know?
When an asteroid hits, it blasts off a lot of debris, which covers the surrounding. Like a blanket.
This debris covered the cracks. But if the cracks formed after the crater, they would have sliced through the debris.
Side-view of the crater
Also, not a single of those 100+ cracks cuts through the crater. They all stop exactly where the crater begins.
The question is, what made those cracks?
See, this crater sits in the middle of a much larger crater, called Caloris Basin. 1500 km across. The 5th largest crater in the Solar system.
Long ago, something happened deep beneath this basin. A massive plume of magma pushed it up. Caused it to bulge outwards.
But the surface is hard. It stretched and cracked.
Caloris Basin. The spider sits in the middle.
The cracks aren't random. They start from a point and spread outwards. Like a crack on your windshield.
Billions of years later, a completely unrelated asteroid hit Mercury. By pure fluke, it slammed exactly where the cracks converged.