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.