NASA’s planet-hunting telescope TESS has found its first Earth-sized exoplanet orbiting a star about 53 light-years from Earth, which is also its smallest-yet identified exoplanet. The planet, named HD 21749c, takes about eight days to orbit its star, scientists revealed. TESS has also found a sub-Neptune exoplanet HD 21749b, which takes 36 days to complete an orbit around its star.

TESS:

• The Transiting Exoplanet Survey Satellite (TESS) is a space telescope for NASA’s Explorers program, designed to search for exoplanets using the transit method in an area 400 times larger than that covered by the Kepler mission.
• It was launched on April 18, 2018 atop a Falcon 9 rocket.
• During its 2-year primary mission, it is expected to find more than 20,000 exoplanets, compared to about 3,800 exoplanets known when it launched.
• TESS uses a novel highly-elliptical orbit around the Earth with an apogee approximately at the distance of the Moon and a perigee of 108,000 km.
• TESS orbits Earth twice during the time the Moon orbits once, a 2:1 resonance with the Moon. The orbit is expected to remain stable for a minimum of 10 years.