Jupiter aurorae. Composite optical and X-ray satellite image of Jupiter. The purple regions at either pole are regions of auroral emissions. These are regions where charged particles moving in the solar wind are caught in the magnetic field surrounding Jupiter. Falling toward the magnetic north and south poles, they collide with molecules and atoms in the upper atmosphere. The atoms become energized and release the extra energy in the form of light. This image is a composite of data taken by the Chandra X-ray observatory and an optical image of Jupiter taken by the Hubble Space Telescope.