NASA’s TESS spacecraft has spotted a roughly Earth-size planet orbiting in its star’s habitable zone, the region defined by temperatures allowing water to exist as a liquid. Image: NASA
NASA’s Transiting Exoplanet Survey Satellite, or TESS, has chalked up two firsts. The exoplanet-hunting spacecraft has spotted its first Earth-size planet orbiting in the host star’s habitable zone. It also has detected its first circumbinary planet, a world the size of Saturn that orbits two stars. Both discoveries were discussed during the winter meeting of the American Astronomical Society in Honolulu.
A Habitable-Zone World Slightly Larger Than Earth
The habitable-zone planet is one of three orbiting a star known as TOI 700, a cool M dwarf with roughly 40 percent of the Sun’s mass located about 100 light-years from Earth. The star initially was misclassified as similar to the Sun in size, which meant its three planets were thought to be larger – and hotter – than they actually are.
Several researchers, including high school student Alton Spencer, found the error.
“When we corrected the star’s parameters, the sizes of its planets dropped, and we realised the outermost one (TOI 700 d) was about the size of Earth and in the ...