Dubai, United Arab Emirates (CNN) – A NASA mission has spotted an exoplanet the size of Earth, orbiting a small star about 100 light-years away. The planet, called TOI 700 e, is likely to be rocky and has a size of 95% the size of our planet.
The celestial body is the fourth planet to be discovered, orbiting the small dwarf star M TOI 700. All of the planets were discovered by NASA’s Transiting Exoplanet Survey satellite of the TESS mission.
There is another planet in the solar system, discovered in 2020 and named TOI 700 d, which is also the size of Earth. All of these exoplanets are in the habitable zone relative to their stars, or at an appropriate distance from the star, for which liquid water is likely to exist on their surfaces.
The possibility of liquid water suggests that the planets themselves could be, or may have once been, habitable for life.
The discovery of the fourth planet was announced, Tuesday, during the 241st meeting of the American Astronomical Society in Seattle, and a study on exoplanets was approved for publication by the Astrophysical Journal.
“This is one of the few systems we know about that includes multiple, minor planets and habitable zones,” Emily Gilbert, associate lead study author at NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement.
“This makes the TOI 700 system an exciting prospect for additional follow-up. Planet e is about 10% smaller than Planet d, so the system also shows how additional observations by TESS are helping us find smaller and smaller worlds,” she added.
Small, gorgeous M dwarf stars like TOI 700 are common in the universe, and many of them have been shown to host exoplanets in recent years, such as the TRAPPIST-1 system and its seven exoplanets to be observed by the James Webb Space Telescope.
While the planet closest to the star, TOI 700 b, which accounts for 90% of the Earth’s size and completes one fast orbit around the star every 10 Earth days. Then there is TOI 700 c, which is 2.5 times more massive than our planet and orbits the star every 16 days. The two planets are likely to always show the same side to the star, much like how the same side of the Moon always faces the Earth.
As for the two planets in the habitable zone, d and e, they have longer orbits of 37 days and 28 days, respectively, because they are a little farther from the star, while the newly discovered planet e is located between planets c and d.
For his part, study co-author Ben Hurd, a doctoral student at Park College at the University of Maryland, said in a statement: “If the star was a little closer or the planet a little larger, we might have been able to detect TOI 700 e in the first year of the TESS mission, but the signal was So faint, that we needed an extra year of observing planetary transits to identify them.”
And as researchers use other space and ground-based observatories to make follow-up observations of the intriguing planetary system, more TESS data is pouring in.
“TESS has just completed its second year of observing the northern part of the sky, and we look forward to other exciting discoveries hidden in the mission’s treasure trove of data,” said Alison Youngblood, TESS’s deputy project astrophysicist at Goddard.