Scientists have been trying to discover Saturn’s secret to looking so young and hot for years.

Put simply, as planets grow older, they typically become darker and cooler. Saturn, however, is exceptionally bright for a planet of its age – a phenomenon that’s puzzled scientists since the late 1960s.

However, scientists from the University of Exeter and Ecole Normale Superieure de Lyon believe they may have finally caught on to the planet's secret.

Their study, published in the journal Nature Geoscience, reveals that Saturn just can’t help itself – instead of heat being transported throughout the planet by large convective motions, as once thought, it appears instead to be partly transferred by diffusion across different layers of gas inside of itself.

“These separate layers effectively insulate the planet and prevent heat from radiating out efficiently,” the group explained in a press release. “This keeps Saturn warm and bright.”

Layered convection has been observed in the Earth’s oceans where warm, salty water lies beneath cooler, less salty water. This denser water prevents vertical currents from forming between different layers, thus preventing the transportation of heat efficiently upwards.

Such findings further suggest that the interior structure, composition and thermal evolution of the Solar System’s gas giants, and beyond, may be much more complex than once thought.

Saturn is one of the largest planets in the Solar System, second only to Jupiter, and is primarily composed of hydrogen and helium. Previously, its excessive brightness was attributed to helium rains, which are the result of helium failing to mix with the planet’s hydrogen-rich atmosphere.

The planet has 60 moons and is the least dense planet in the Solar System; in fact, if there were a bathtub big enough to fit the massive planet, it would float in it.

The study was funded by the European Research Council.