TESS Spacecraft Discovered An Earth-Sized Planet 53 Light-Years Away

NASA is bragging on the TESS (Transitioning Exoplanet Survey Satellite) spacecraft as it has discovered its very first Earth-sized world. TESS has found a planet dubbed HD 21749c that scientists say is about 89% of Earth's diameter making it a bit smaller than our planet. The planet orbits a star called HD 21749.

That star is a K-type star that is about 70% of the Sun's mass and is 53 light-years away from Earth in the southern constellation called Reticulum. HD 21749c is the second planet that TESS has identified in that star system.

The planet is believed to be rocky and orbits very close to its host star. A single orbit takes the planet only eight days according to NASA. Orbiting so close to the host star means the planet is likely very hot with surface temperatures that are as high as 800-degrees Fahrenheit.

While this is the second planet discovered in this particular star system, the discovery is TESS' tenth planetary find overall. TESS has discovered "hundreds" of additional candidates that are being studied. That means the door is open for TESS to add significantly more planetary discoveries to its books. TESS' findings for HD 21749c were confirmed by scientists from MIT and the Carnegie Institution for Science by analyzing data from the first four sectors of TESS observations.

That analysis showed 11 periodic dips in the brightness of the host star in the system indicating a planet was orbiting the star. The scientists determined that the star's light was partially blocked by a planet about the size of Earth. While 53 light-years is a vast distance, the system is close enough for more detailed follow-up studies, including a potential first mass measurement of an Earth-sized planet found by TESS.