Mercury was heavily bombarded by comets and asteroids during and shortly following its formation 4.6 billion years ago, as well as during a possibly separate subsequent episode called the Late Heavy Bombardment that ended 3.8 billion years ago.
Merkur blev oprindeligt bombarderet med kometer og asteroider under og kort efter sin dannelse 4,6 milliarder år siden og muligvis også i en senere periode kaldet Late Heavy Bombardment, der sluttede for 3,8 milliarder år siden.