Enormous Planet With Glowing Water Atmosphere – It’s Hot Enough To Boil Iron

Outside our solar system there is an enormous planet with glowing water atmosphere. The temperature is so high there, that it’s hot enough to boil iron!

The planet in question is named WASP-121b. It’s a “hot Jupiter” located approximately 900 light years from Earth.

WASP-121b has a greater mass and radius than Jupiter, making it much puffier.

The exoplanet orbits its host star every 1.3 days, and the two bodies are about as close as they can be to each other without the star’s gravity ripping the planet apart. This close proximity also means that the top of the atmosphere is heated to a blazing hot 2,500 degrees Celsius — the temperature at which iron exists in gas rather than solid form.

Scientists from the University of Exeter and University of Maryland have discovered glowing water molecules in WASP-121b’s atmosphere.

Researchers have found that a “hot Jupiter” exoplanet named WASP-121b (left) has a stratosphere hot enough to boil iron. The planet is as close to its host star (right) as possible without the star’s gravity ripping the planet apart.Credit: Engine House VFX, At-Bristol Science Centre, University of Exeter

Previous research spanning the past decade has indicated possible evidence for stratospheres on other exoplanets, but this is the first time that glowing water molecules have been detected — the clearest signal yet to indicate an exoplanet stratosphere.

“When it comes to distant exoplanets, which we can’t see in the same detail as other planets here in our own solar system, we have to rely on proxy techniques to reveal their structure,” said Drake Deming, a professor of astronomy at UMD and a co-author of the study. “The stratosphere of WASP-121b so hot it can make water vapor glow, which is the basis for our analysis.”

The stratosphere of WASP-121b so hot it can make water vapor glow, but why is this happening?

In Earth’s stratosphere, ozone traps ultraviolet radiation from the sun, which raises the temperature of this layer of atmosphere. Other solar system bodies have stratospheres, too — methane is responsible for heating in the stratospheres of Jupiter and Saturn’s moon Titan, for example.

In solar system planets, the change in temperature within a stratosphere is typically less than 100 degrees Celsius. However, on WASP-121b, the temperature in the stratosphere rises by 1,000 degrees Celsius.

“We’ve measured a strong rise in the temperature of WASP-121b’s atmosphere at higher altitudes, but we don’t yet know what’s causing this dramatic heating,” said Nikolay Nikolov, co-author and research fellow at the University of Exeter. “We hope to address this mystery with upcoming observations at other wavelengths.”