Weather forecast for Kepler 12-Ab: sunscreen snow

Contributed by
Nov 2, 2017

Exoplanet Kepler 13-Ab can rocket to temperatures of 5,000 degrees Fahrenheit, but it also makes its own sunscreen.

Astronauts aren’t about to touch down there anytime soon, even if SPF falls to the surface in the form of titanium dioxide snow. The problem is that it only snows on the night side of the tidally locked planet and sears on the other. You’d have to either bottle that snow somehow or roll around in it without a space suit on (not an option if you actually want to breathe) before trekking over to the unfathomably hot day side—that is, if any human could actually enter that kind of inferno and make it out alive.

The sunscreen snow (oxymoron right there) was discovered by Hubble, which can always be counted on to unearth weird things in space. NASA Hubble astronomers believe titanium oxide gas on Kepler 13-Ab is blown to the night side by intense winds, where it condenses into snowflakes that accumulate into clouds until they are forced from the upper atmosphere into the lower atmosphere of this “hot Jupiter” by gravity six times as powerful as Jupiter’s. If you know anything about Jovian gravity, it would insta-flatten you.


Titanium oxide was discovered by the astronomers as they questioned why the atmosphere of Kepler 13-Ab cools off at higher altitudes instead of heating up like the upper atmospheres of other hot Jupiters. Light-absorbing titanium oxide gas is common on these types of gas giants, which are many times more sweltering than your worst summer ever because they hang out so close to their stars. The Hubble research team concluded that the anomaly in Kepler 13-Ab was the absence of titanium oxide on the day side. Gaseous titanium oxide absorbs starlight and re-radiates it as heat, which explains why temps creep up as you venture higher into the atmosphere.

Kepler 13-Ab is one of the hottest known planets and obviously nowhere near habitable, but besides providing insight into exoplanet weather forecasts, its conditions can eventually be used to better understand super-Earths where there could potentially be life. Hot Jupiters are a portal into extraterrestrial climates. Even though they are inhospitable themselves, and the gravity alone would crush anything alive, they will be valuable when NASA zeroes in on smaller planets that may have more complex atmospheres but less visibility.

"In many ways, the atmospheric studies we're doing on hot Jupiters now are testbeds for how we're going to do atmospheric studies on terrestrial, Earth-like planets," said Thomas Beatty, lead researcher of a study recently published in The Astronomical Journal.

Beatty theorizes that it snows sunscreen on most hot Jupiters. Their lower surface gravities just mean that the snow doesn’t make it past the upper atmosphere before it blows over to the blistering dayside and revaporizes.

For now, flying 1,730 light-years away isn’t worth it for an unlimited supply of free SPF—just stock up on the bottled stuff.

(via NASA)