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Largest impact basin on Mercury

Largest impact basin on Mercury
Who
Caloris Basin
Where
Not Applicable
When
1974
The largest impact basin on Mercury is the Caloris Basin, which measures about 1,550 km across. It was formed around 3.8–3.9 billion years ago when an object at least 100 km in diameter struck the planet. It is surrounded by mountains that reach about 2 km in height. It was discovered in 1974 by NASA's Mariner 10 spacecraft and has since been imaged in more detail by NASA's Messenger spacecraft.