Earth-Sized, Potentially Habitable Planet Discovered 100 Light-Years Away

Less than two years after starting its mission, NASA's Transiting Exoplanet Survey Satellite, or TESS, has found what may be its first habitable planet, CNN reports.

The body orbits the cool M-dwarf star TOI 700 in the Dorado constellation 100 light-years away from Earth. According to NASA, the planet, dubbed TOI 700 d, is about 20 percent larger than our own and it sits at just the right distance from its sun to support liquid water. It's one of three planets in the solar system, the others likely being an Earth-sized rocky planet and a gas planet 2.6 times the size of Earth. TOI 700 d is believed to be tidally locked, meaning only one half faces the sun at all times, and orbits there last approximately 37 Earth days.

NASA launched TESS in April 2018 with the goal of discovering planets outside our solar system, including those with the potential to host life. The satellite was built to locate Earth-sized planets orbiting neighboring stars, but this recent discovery almost went undetected. The star TOI 700 was initially thought to be as hot as our own sun, which would have made TOI 700 d uninhabitable. Upon closer inspection, researchers noticed the star was actually relatively cool and small, potentially placing TOI 700 d in the Goldilocks zone for nurturing life.

After TESS's finding was confirmed using the infrared technology of NASA's Spitzer Space Telescope, researchers further studied the planet by modeling its potential atmosphere and surface conditions. These computer models can give astronomers an idea of just how hospitable TOI 700 d is before future missions, such as NASA's James Webb Space Telescope launching in 2021, can collect more evidence.

TOI 700 d may be one of the closest known habitable planets to Earth, but that doesn't mean humans will be visiting it anytime soon. To put the 100 light-year distance into perspective, Mars is less than half a light-year away from Earth, and it can take seven months to get there.