Over two million years ago, a giant asteroid slammed into Mars, scarring the surface with one massive crater and around two billion smaller individual craters. These secondary craters appear across a region of 1,000 miles (1,800 kilometers), making this asteroid event one of the biggest impacts seen on the Red Planet in relatively recent history.
Asteroids massive enough to create widespread destruction like this are estimated to impact Mars just once every 3 million years.
