Scientists Find Planet Where It Rains Molten Rock
You could argue that Earth hasn’t been an ideal place to live lately, but it could be worse. Scientists from Canada’s McGill University have released a new analysis of an exoplanet called K2-141b. This world orbits its star so closely that its ecosystem is profoundly hellish. The ground is rock, the seas are rock, and yes, even the air is rock.
Astronomers first detected K2-141b several years ago — it has the distinction of being the first planet identified during the Kepler Space Telescope’s “second light” mission, often called K2. It’s a few hundred light-years away, making it an impractical vacation spot. Not that you’d want to go anyway with a 100 percent chance of flaming rock storms spoiling all your outdoor activities.
K2-141b is such a hellscape because it’s dense, rocky, and orbits incredibly close to its star. The planet has a density in the neighborhood of Earth’s, so we have reasonably good models to estimate its conditions. Like most close-orbiting planets, K2-141b is tidally locked to the star. That means one side gets roasted during an eternal day while the other is locked in permanent night. This dynamic is what makes K2-141b so inhospitable — if it rotated, things wouldn’t be nearly so deadly.
On the day-side, temperatures on K2-141b can reach 5,400 degrees Fahrenheit (2,982 degrees Celsius). That’s hot enough to melt rock, creating seas of lava to cover most of the surface to a depth of tens of miles. It’s also hot enough to completely vaporize rock to create a thin, scorching atmosphere. On the far side of K2-141b, the temperatures are roughly -328 degrees Fahrenheit (-200 degrees Celsius), which is substantially below the melting point of rock. So, as the vaporized rock atmosphere wafts over to that side, it falls back to the ground. Earth has a water cycle, but K2-141b has a rock cycle. It’s fascinating! But also incredibly hostile to life as we know it.
We don’t know the exact composition of K2-141b, so the team had to create a few models to describe a world with rock-based rain. For example, if the atmosphere is mostly silica or silicon monoxide, the “rain” would be molten rock, like a volcanic eruption that never ends. If the crust is high in sodium, the rain would slosh back into the molten oceans like glaciers on Earth.
Of course, this is all an educated guess based on our limited data on K2-141b. We might find out how close this is to reality in the next few years. Scientists believe the upcoming James Webb Space Telescope will be able to scan the atmospheres of some exoplanets like K2-141b. NASA hopes to get this telescope into space in 2021.