NASA discovers second Earth-sized planet in 'habitable zone'
NASA scientists discover the fourth planet in the TOI 700 system that could have liquid water on it.
Using data from the Transiting Exoplanet Survey Satellite, NASA scientists have discovered a world that is likely rocky and 95% of the size of Earth called TOI 700 e, which is orbiting around a star and could have liquid water on it.
According to NASA, this is the fourth planet discovered in the TOI 700 system after TOI 700 b, c, and d. TOI 700 is a star that the planets orbit around, but only d and e orbit in the habitable zone, which is the range of distance from a star where liquid surface water could be present at some point in a planet’s history.
"This is one of only a few systems with multiple, small, habitable-zone planets that we know of," highlighted Emily Gilbert, a postdoctoral fellow at NASA's Jet Propulsion Laboratory in Southern California, adding that this "makes the TOI 700 system an exciting prospect for additional follow up."
Gilbert, who led the work, pointed out that the newly discovered planet e is 10% smaller than planet d, adding that TOI 700 e takes 28 days to orbit its star, while d takes 37 days.
It is noteworthy that the team discovered the planets during Transiting Exoplanet Survey Satellite (TESS) observations, which were designed to discover additional planets and stars. The satellite monitors large swaths of the sky called sectors for approximately 27 days at a time.
"If the star was a little closer or the planet a little bigger, we might have been able to spot TOI 700 e in the first year of TESS data," said Ben Hord, a graduate researcher at NASA's Goddard Space Flight Center. "But the signal was so faint that we needed the additional year of transit observations to identify it," he indicated.
According to NASA, TESS has created imaging for about 75% of the sky and found 66 new exoplanets or worlds beyond the Earth's solar system.
Gilbert said that the new discovery of TOI 700 e proves that TESS can help "us find smaller and smaller worlds."
NASA explained that "finding other systems with Earth-size worlds in this region helps planetary scientists learn more about the history of our own solar system."