Saturn: the Blue Planet? The NASA/ESA Hubble Space Telescope reveals the secrets of the giant planet.
This false colour image from the Hubble Space Telescope not only shows Saturn in an unfamiliar light, but displays some of the giant planet’s features.
The image was created in early 2009, when Saturn was nearing an equinox, the time when light from the Sun is falling perpendicularly on the planet’s equator. Here on Earth, we are familiar with the spring and autumn equinoxes when day and night are equally long. Saturn experiences two equinoxes per Saturnian year (about thirty Earth years). Saturn’s next equinox will not be for another 15 years.
Viewing Saturn at this time not only allows us to see the famous rings almost edge on but also to observe both polar regions at once. There we see Saturn’s aurorae, analogous to Earth’s Northern lights and Southern Lights. On both Earth and Saturn these are caused when electrically charged particles from the Sun are caught in the planets’ magnetic fields. This concentrates the particles at the poles where each planet’s magnetic field is strongest. The particles crash into atoms of gas in the upper atmosphere releasing energy, some of which we see as light.
Note that Saturn is not a perfect sphere. A gas giant planet, it rotates more like a ball of fluid than a solid ball like Earth. It also rotates on its axis relatively quickly(its day is about ten hour and a half hours long) so the spin has effectively flattened it slightly.
Another amazing image from the HST!