TRAPPIST-1 Planets Could Contain 250 Times More Water Than Earth

Saturday, 10 February 2018 - 12:19PM
Space
Earth
Saturday, 10 February 2018 - 12:19PM
TRAPPIST-1 Planets Could Contain 250 Times More Water Than Earth
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NASA/JPL-Caltech
The seven planets orbiting around the nearby (or relatively nearby, about 40 lightyears away) TRAPPIST-1 star have been making headlines throughout the past year, because of how potentially similar to Earth they are.

And beyond being Earth-sized and having apparent atmospheres, we're now finding more evidence that the TRAPPIST-1 planets are filled with water. According to a new study published in Astronomy & Astrophysics, a team of researchers at the University of Bern in Switzerland analyzed one of the few things we can study from 40 lightyears away - such as the planets' gravitational pulls on each other - to figure out details about their compositions and density.

With these calculations, the team was able to make some more precise calculations about the planets than what we'd been using previously, and they determined that all seven planets consist of mainly rock and contain up to five percent water. Now, that "up to five percent" part is important to remember, but if each planet really does have that much water, it would be 250 times more water than what's found in Earth's oceans.



It helps that the planets are packed together so closely that they have a strong influence on each others' orbits, and if you were to stand on the surface of one, you could easily see the others in the night sky. Simon Grimm, the head of this research team at the University of Bern, explained how this helped his process in a press release:

Opening quote
"In the TRAPPIST-1 system, the planets are so close together that they perturb each other. This causes a slight shift in the times of each transit. Using a computer model, one can simulate the planetary orbits until the calculated transits agree with the observed values, which thus also yields the planets' masses."
Closing quote




Of course, the planets aren't identical to each other, and some almost surely have more water than others. The system's outermost planets like TRAPPIST-1g and TRAPPIST-1h are likely frozen planets with mostly ice, while the closest planets like TRAPPIST-1b and TRAPPIST-1c have dense atmospheres that would prevent us from easily reaching that water anyway.

If we ever did make it to the TRAPPIST-1 solar system, the planet TRAPPIST-1e would be our best bet, having a rocky surface and a thin atmosphere and liquid water. We still have to get there, but it's nice to know that if we ever leave our own solar system, we'll have a destination in mind that we're reasonably sure about.
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