It is too hot. Other planets which are further from the sun are too cold.
Mars has icecaps and volcanoes, wind and clouds. Once it had water, but now all the water is frozen in the icecaps.
At night the temperature at the equator drops to -111°C.
The Viking Lander took this picture of the surface of Mars in 1976.

Space probes explore the solar system and take photos if different planets.
This tells us a lot about our solar system.
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