The dancing light of the auroras on Saturn behaves differently from how scientists had thought possible. By choreographing the instruments aboard the Earth-orbiting Hubble Space Telescope and the Cassini spacecraft, while it was enroute to Saturn, to look at Saturn's southern polar region, scientists found in 2005 that the planet's auroras, long thought of as a cross between those of Earth and Jupiter, are fundamentally unlike those observed on either of the other two planets.
What causes the structure in Comet Lovejoy's tail? Comet C/2014 Q2 (Lovejoy), which is currently at naked-eye brightness and near its brightest, has been showing an exquisitely detailed ion tail. As the name implies, the ion tail is made of ionized gas -- gas energized by ultraviolet light from the Sun and pushed outward by the solar wind. The solar wind is quite structured and sculpted by the Sun's complex and ever changing magnetic field. The effect of the variable solar wind combined with different gas jets venting from the comet's nucleus accounts for the tail's complex structure. Following the wind, structure in Comet Lovejoy's tail can be seen to move outward from the Sun even alter its wavy appearance over time. The blue color of the ion tail is dominated by recombining carbon monoxide molecules, while the green color of the coma surrounding the head of the comet is created mostly by a slight amount of recombiningdiatomic carbon molecules.