Second Earth-Size World Discovered by NASA Within ‘Habitable Zone’


NASA mission discovered a second Earth-sized, rocky planet within the habitable zone of its star has. The range of distances where liquid water could occur on a planet’s surface.

The astronomers found “TOI 700 e” which is one of only a few systems with multiple, small, habitable-zone planets that we know of Using data from NASA’s Transiting Exoplanet Survey Satellite (TESS).

Astronomers previously discovered three planets in this system, called TOI 700 b, c, and d. Planet d also orbits in the habitable zone, but the scientists needed an additional year of TESS observations to discover TOI 700 e.


Emily Gilbert, a postdoctoral fellow at NASA’s Jet Propulsion Laboratory in Southern California who led the work said “That makes the TOI 700 system an exciting prospect for additional follow up. Planet e is about 10 per cent smaller than planet d, so the system also shows how additional TESS observations help us find smaller and smaller worlds.”

TOI 700 is a small, cool M dwarf star located around 100 light-years away in the southern constellation Dorado. The innermost planet, TOI 700 b, is about 90 per cent Earth’s size and orbits the star every 10 days. TOI 700 c is over 2.5 times bigger than Earth and completes an orbit every 16 days. In 2020, Gilbert and others announced the discovery of the Earth-size, habitable-zone planet d, which is on a 37-day orbit, along with two other worlds.

The US space agency said in a statement late on Tuesday “The planets are probably tidally locked, which means they spin only once per orbit such that one side always faces the star, just as one side of the Moon is always turned toward Earth.”

TOI 700 e, which may also be tidally locked, takes 28 days to orbit its star, placing planet e between planets c and d in the so-called optimistic habitable zone. The optimistic habitable zone is defined by Scientists as the range of distances from a star where liquid surface water could be present at some point in a planet’s history.


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