This image was taken by the Hubble Space Telescope. It is one of the rarer images where Uranus' ring system is visible. The blue colour of Uranus suggests that there might be water on the planet, but the colour is caused by a layer of methane in the upper atmosphere. Methane molecules hold back the red part of reflected sunlight, but they let the blue part of the light pass through. Due to its high axial tilt, Uranus' poles lie approximately within the plain of the Solar System.