Half a billion miles away from Earth, this blue aurora glows in the atmosphere around Jupiter. Taken by the Hubble Space Telescope on December 14, 2000, the image shows the aurora centered over the planet's magnetic north pole. Auroral displays have been observed on Jupiter, Saturn, Uranus, and Neptune, as well as on the moons of these planets. The process for generating auroras is the same throughout the solar system; the only requirements for auroras are the presence of a magnetosphere and an atmosphere. Interestingly, Jupiter's moon Io does not have an atmosphere surrounding it, but its many active volcanoes can create temporary atmospheres around them when they erupt, allowing for eerie, ground-level auroras.