Newton Crater on Mars with evidence of recent liquid water
The basin was formed by an asteroid impact some 3 billion years ago, and measures approximately 287 kilometres (178 miles) across. Within the Newton Crater there is a smaller crater also formed by an asteroid impact, and measures around 7 kilometres (4.4 miles) across. The north wall of the small crater is shown in the picture with its gullies thought to be formed by water and debris flows. Image by Mars Orbiter Camera, NASA, 2000.