How Saturn Maintains its Bright, Youthful Appearance: It's Not Plastic Surgery

If Saturn were human, it would have had a lot of plastic surgery--or just have some really great genes. The planet looks a lot younger than it should with its bright surface, a phenomenon that has puzzled scientists since the late sixties. Now, researchers have discovered exactly how Saturn keeps itself looking so young--and it's not the fountain of youth.

When planets age, they become much darker and cooler. Saturn, in contrast, has remained relatively hot and bright. In order to find out why, researchers examined the planet a bit more closely, measuring temperatures and looking at the structure of Saturn itself.

It turns out that Saturn looks so young because it simply has trouble cooling down. Saturn is a gas giant, characterized by its distinctive rings. It's also physically unstable deep within its core; this instability actually prevents heat from escaping and has kept Saturn from cooling down.

"Scientists have been wondering for years if Saturn was using an additional source of energy to look so bright, but instead our calculations show that Saturn appears young because it can't cool down," said Gilles Chabrier from Physics & Astronomy at the University of Exeter in a news release. "Instead of heat being transported throughout the planet by large scale (convective) motions, as previously thought, it must be partly transferred by diffusion across different layers of gas inside Saturn."

It's these separate gas layers that cause the phenomenon. Like layers of blankets, they insulate the planet and prevent heat from radiating out effectively into space. This, in turn, keeps Saturn warm and bright.

In fact, layered convention, like what was discovered in Saturn, has been observed in Earth's oceans. Warm, salty water lies beneath cool and less salty water. The denser, salty water actually prevents vertical currents from forming between the different layers. This, in turn, prevents heat from being transported efficiently upward.

The findings reveal that the interior structure, composition and thermal evolution of giant planets in our Solar System are far more complex than previously thought. It has major implications for the study of gas giants, such as Saturn and Jupiter, which can be mostly composed of hydrogen and helium.

The findings are published in the journal Nature Geoscience.