It might sound like something from science fiction, but NASA scientists have just found a blisteringly hot planet where it actually ‘snows’ suncream.
The Hubble telescope was scanning exoplanet Kepler-13Ab, located outside of our solar system, when they found the vicious storms of titanium dioxide - the active ingredient in sunscreen - raining down.
But sadly visitors wouldn’t be able to bottle it up to defend themselves against the 5000-degree daytime temperatures on Kepler 13-Ab, because it only falls on the side of the planet permanently kept in darkness away from the parent star. Typical.
The team of astronomers at Penn State didn’t go looking for the titanium dioxide but were studying Kepler-13Ab as it is one of the hottest known exoplanets and so is able to provide insight into the complexity of weather and atmospheric conditions.
And may someday be useful for gauging the habitability of earth-sized planets.
Lead author Thomas Beatty said: “In many ways, the atmospheric studies we’re doing now on these gaseous ‘hot Jupiter’ kind of planets are test beds for how we’re going to do atmospheric studies of terrestrial, Earth-like planets.”
During their exploration they found that the planet’s atmosphere is cooler at higher altitudes, which was surprising because it is the complete opposite of what happens on other hot Jupiters.
They concluded there must be something at play causing this to happen, and made the first detections of this “snow-out” process ever recorded.
Working as a cold-trap, the team speculated that instead of absorbing light and re-radiating it as heat (as is seen on other planets) Kepler-13Ab’s titanium oxide is missing from the daytime side.
And as a result the lack of titanium oxide gas to absorb incoming starlight means the atmospheric temperature there grows colder with increasing altitude.
The reason it is missing in the first place is because powerful winds carry it around, condensing it into crystalline flakes that form clouds.
Jason Wright, study co-author, explained why it is so important to understand these exoplanet conditions, saying: “Understanding what sets the climates of other worlds has been one of the big puzzles of the last decade, seeing this cold-trap process in action provides us with a long sought and important piece of that puzzle.”
The team’s observations also support the idea that this happens on other planets too, of a similar size, but you just can’t see it.
“Presumably, this precipitation process is happening on most of the observed hot Jupiters, but those gas giants all have lower surface gravities than Kepler-13Ab.
“The titanium oxide snow doesn’t fall far enough in those atmospheres, and then it gets swept back to the hotter dayside, revaporizes, and returns to a gaseous state,” said Beatty.