Moon rising over Earth's horizon, composite image. The blue haze of Earth's atmosphere can be seen above the horizon. Earth is thought to be the only planet in the solar system that can support life. The Moon (at centre) has a diameter just over a quarter of the Earth's. It orbits at a distance of around 385,000 kilometres, taking nearly 30 days for one orbit. It does not have an atmosphere and is a heavily cratered and barren piece of rock.