Take a look at these fantastic images of Mars, showing craters, ridges and sand dunes on the surface of the planet.
Nasa scientists have managed to get these fantastic images of the surface of Mars. Here's a crater on the planet. Around it is the material that was thrown out after the impact that created it.
These fan-shaped deposits suggest there's a delta, that forms when water in a channel flows into a larger area and as the water spreads out, it moves more slowly and drops the sediment that it's carrying.
Here's a picture of a ridge known as a wrinkle ridge. At the top, is a freshly-created crater - you can tell it's recent because it has quite a sharp rim. The images are from Nasa's HiRISE telescope, orbiting the planet.
Sand dunes like these are among the most common wind-formed features on Mars - the strength and direction of the wind affects the way the sand dunes look.