NASA's TESS Satellite Discovers Earth-Sized Planet That May be Habitable

The planet is in the zone where conditions are ideal for liquid water to be on the surface.
Donna Fuscaldo

NASA's Transiting Exoplanet Survey Satellite or TESS discovered its first Earth-size planet in its star's habitable zone. 

In a press release, NASA said the planet is in the range of distances where the conditions could be ideal for liquid water to be on the surface of the planet.

Scientists were able to confirm the planet which they named TOI 700.  They have already modeled what they think the planet's environments may look like to help when observing the planet in the future. 


TO1 700 planets
Three planets of the TOI 700 system. Source: NASA 

"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 in a press release. "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."

TOI 700 is a small, cool planet 

According to NASA TOI 700 is a small, cool M dwarf star that is slightly more than 100 light-years away. It was found in Dorado, the southern constellation. NASA said the planet is about 40% of the Sun's mass and size and its surface temperatures are about half of the sun.

It appeared in 11 of the 13 sectors the TESS observed during year one of the mission.  The star had been previously misclassified as being more like the Sun. The mistake was eventually corrected changing the makeup of the planet. 

"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 in the press release. "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."