NASA Mission Discovers First Potentially Habitable Earth-Sized Planet

NASA's Transiting Exoplanet Survey Satellite (TESS) has made an exciting new discovery that could help further the search to find a future home for the human race.

The planet hunter, as the spacecraft is also known, found its first Earth-sized planet in a zone where conditions may allow the presence of liquid water on the surface.

The potentially habitable planet named TOI 700 d is located 100 light-years away in the southern constellation Dorado.

"TESS was designed and launched specifically to find Earth-sized planets orbiting nearby stars," said Paul Hertz, astrophysics division director at NASA Headquarters in Washington, D.C. "Planets around nearby stars are easiest to follow-up with larger telescopes in space and on Earth. Discovering TOI 700 d is a key science finding for TESS. Confirming the planet's size and habitable zone status with Spitzer is another win for Spitzer as it approaches the end of science operations this January."

Scientists used NASA's Spitzer Space Telescope to confirm the findings and have modeled the planet's potential environment to inform future observations.

TOI 700 is a small, cool M dwarf star. It's roughly 40% of the sun's mass and size, and about half the sun's surface temperature. TOI 700d is one of three planets tidally locked to the dwarf star, which was originally misclassified as being similar to our sun.

"When we corrected the star's parameters, the sizes of its planets dropped, and we realized the outermost one was about the size of Earth and in the habitable zone," said Emily Gilbert, a graduate student at the University of Chicago. "Additionally, in 11 months of data we saw no flares from the star, which improves the chances TOI 700 d is habitable and makes it easier to model its atmospheric and surface conditions."

The other two planets orbiting the star, TOI 700 b and c, were found to be too rocky or gassy to be inhabitable. While we don't know the exact conditions on TOI 700 d, NASA scientists say they can use what we do know — like the planet’s size and the type of star it orbits — to make predictions about what's possible on this newfound planet.