NASA's the Transiting Exoplanet Survey Satellite (TESS) has discovered an Earth-sized planet, HD 21749b and a "sub-Neptune" world, revolving around the star, HD 21749. The star lies 53 light-years from Earth. The research study has been published on 15th April, 2019 in 'The Astrophysical Journal Letters'. TESS was launched to Earth orbit in April 2018 on a SpaceX Falcon 9 rocket. One tool termed as 'Planet Finder Spectrograph' (PFS) on the 'Magellan II telescope' in Chile helped to confirm the planetary nature of the TESS signal and measure the mass of HD 21749b. HD 21749b is about 23 times heavier and 2.7 times wider than Earth. It is gaseous, has a substantial atmosphere but not as puffy as Uranus and Neptune. HD 21749b has an orbital period of 36 Earth days.
