Far, far away

Look! Astronomers find a new habitable zone planet hiding from them

It’s not the only potentially habitable world in the TOI-700 system.

NASA/JPL-Caltech/Robert Hurt

NASA's Goddard Space Flight Center/Chris Smith (USRA)

Of all the planets orbiting red dwarf star TOI-700, just one roughly Earth-sized world seemed to hold promise for hosting extraterrestrial life.

NASA/JPL-Caltech/Robert Hurt

That was until astronomers took a closer look.

This week, a team led by NASA scientists announced that a second planet was just discovered in TOI-700’s habitable zone.

Meet TOI-700 e.

The newly-named, potentially rocky exoplanet orbits slightly closer to its star than sister planet TOI-700 d. It is similar in size to Venus.

NASA/JPL-Caltech/Robert Hurt

NASA's Goddard Space Flight Center

The planet was discovered with NASA’s Transiting Exoplanet Survey Satellite (TESS), and took an additional year to locate because of its smaller size.

Astronomers tracked each time the planet passed in front of its host star, discovering that it takes about 28 days to complete one orbit.

NASA’s Goddard Space Flight Center

NASA/JPL-Caltech/Robert Hurt

The planet is 95 percent the size of Earth.

And it's one of the few small, or sub-Earth, exoplanets known to be in a star system’s habitable zone.

NASA's Goddard Space Flight Center/Chris Smith (USRA)

Its order in TOI-700 system might be a little confusing: planet e is located between planet c and planet d.

That’s simply due to the fact that it was discovered most recently.

This was the system before planet e was discovered. Note that planet d is the only one in the conservative habitable zone.

NASA’s Goddard Space Flight Center

Now, scientists place planet e in the optimistic habitable zone.

NASA’s Goddard Space Flight Center

NASA/JPL-Caltech/Robert Hurt

That means planet e probably had liquid water on its surface at some point during its lifetime.

Pavirakit Songkhao / EyeEm/EyeEm/Getty Images

Planet d, on the other hand, is more likely to have had surface water over most of its lifetime.

Whether either of these worlds can host life remains to be seen, but the TOI-700 system is looking more and more promising.

NASA/JPL-Caltech/Robert Hurt

NASA/JPL-Caltech/Robert Hurt

“This is one of only a few systems with multiple, small, habitable-zone planets that we know of.”

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