There was a common wisdom among scientists regarding extremely hot rocky planets that orbit their sun closely. Some wisdom that makes a ton of sense: the closer a planet is to a sun, the less of a chance that it has an atmosphere. After all, it probably would have been burnt and blasted into space.
Well, a new study using NASA’s James Webb Space Telescope just made that assumption a lot harder to defend; it’s all thanks to a planet called TOI-551 b.
TOI-551 b is a so-called “super-Earth” that orbits a 10 billion-year-old star that’s about 280 light-years away. It’s so close to its sun (about 11 million miles away) that it completes its orbit in just 11 hours.
This means it’s close enough for tidal locking, meaning one side is permanently roasting while the other side is engulfed in an endless night. The old assumptions hold that this planet should be either a barren, rocky, airless void or a churning ball of exposed lava.
But Webb’s observations suggest otherwise.
‘Wet Lava Ball’ Planet Might Actually Have an Atmosphere, NASA Says
TOI-561 b has a weirdly low density, too low to be explained by rock alone. According to research published in The Astrophysical Journal Letters, using Webb’s Near-Infrared Spectrograph, researchers measured the planet’s dayside temperature. They found it hovering around 3,200 degrees Fahrenheit.
That’s extreme, but not extreme enough, all things considered. If the planet had no atmosphere to redistribute heat, temperatures should be closer to 4,900 degrees. Looks like something is buffering the heat. But what?
After testing several theories, the researchers landed on the one that challenged the most assumptions: this tiny rocky planet, too close to the sun, might have the exact kind of atmosphere that all common wisdom suggests it should not have.
Given all we know about how planets work, the only way to explain the lower-than-expected temperatures is if the Earth had a substantial blanket of gases surrounding it capable of moving heat from the dayside of the planet to the nightside. The atmosphere would also help explain the planet’s low density, which also doesn’t match what we expect from a purely rocky world.
As you’d expect, this creates a whole new puzzle to solve: how does a small planet getting constantly bombarded by radiation hold onto an atmosphere at all? The researchers suspect that it has something to do with its vast ocean of magma.
They also suspect that it is creating a feedback loop where gases escape from the surface to form an atmosphere. At the same time, the magma simultaneously absorbs gases back into the planet’s interior. This creates an uneasy balance that keeps the planet intact instead of blowing itself apart.
Pretty wild, right?
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