TESS discovers its first Earth-sized planet
NASA’s Transiting Exoplanet Survey Satellite, TESS, has discovered its first Earth-sized exoplanet. The planet, named HD 21749c, is the smallest world outside our solar system that TESS has identified yet. In a paper published today in the journal Astrophysical Journal Letters, an MIT-led team of astronomers reports that the new planet orbits the star HD 21749 — a very nearby star, just 52 light years from Earth. The star also hosts a second planet — HD 21749b — a warm “sub-Neptune” with a longer, 36-day orbit, which the team reported previously and now details further in the current paper. The new Earth-sized planet is likely a rocky though uninhabitable world, as it circles its star in just 7.8 days — a relatively tight orbit that would generate surface temperatures on the planet of up to 800 degrees Fahrenheit. The discovery of this Earth-sized world is nevertheless exciting, as it demonstrates TESS’ ability to...