NASA's Transiting Exoplanet Survey Satellite (TESS) has found a potentially habitable Earth-sized planet orbiting around a star in the range of distances. The experts believe that the conditions could allow the presence of liquid water on the planet's surface.

According to a statement from NASA's Jet Propulsion Laboratory (JPL) in Pasadena, the scientists used Spitzer Space Telescope to confirm the latest discovery of the planet, dubbed TOI 700 d. The scientists said that TOI 700 d, which is a small, cool M dwarf star, is located more than 100 light-years away in the southern constellation Dorado.

Discovery of TOI 700 d

New planet
In a galaxy 100 light-years away in the constellation Dorado sits a planetary system named TOI 700. It is home to TOI 700 d, the first Earth-size habitable-zone planet discovered by TESS, NASA's Transiting Exoplanet Survey Satellite NASA/Goddard Space Flight Center

Reports explained that TESS discovered three planets in orbit, named TOI 700 b, c and d. However, only "d" is in the so-called habitable zone, which is not too far from the star.

Paul Hertz, astrophysics division director at NASA Headquarters in Washington, in a statement: "TESS was designed and launched specifically to find Earth-sized planets orbiting nearby stars. Planets around nearby stars are easiest to follow-up with larger telescopes in space and on Earth. Discovering TOI 700 d is a key science finding for TESS. Confirming the planet's size and habitable zone status with Spitzer is another win for Spitzer as it approaches the end of science operations this January."

JPL said that the new planet joins other Earth-sized planets that were discovered by NASA, including several in the TRAPPIST-1 system, and other worlds discovered by the Kepler Space Telescope.

Misclassification of the star

TESS had initially misclassified the star, which meant the planets appeared larger and hotter than they actually are. But later the error was identified by several amateur astronomers, including high school student Alton Spencer - who works with members of the TESS team.

Emily Gilbert, a graduate student at the University of Chicago, said: "When we corrected the star's parameters, the sizes of its planets dropped, and we realized the outermost one was about the size of Earth and in the habitable zone. Additionally, in 11 months of data, we saw no flares from the star, which improves the chances TOI 700 d is habitable and makes it easier to model its atmospheric and surface conditions."

Composition of the star

According to JPL, the planet that is nearest to the star is almost exactly the same size as the Earth and it takes 10 days to complete its orbit. The middle planet of the star is 2.6 times larger than Earth and has a 16-day-long orbit.

The outermost planet, existing in the habitable zone, is 20% larger than the Earth and takes 37 days to complete its orbit. It receives about 86% of the energy from its star that Earth receives from the Sun.

The scientists suggested that all the planets are tidally locked to their star and noted that the cloud formations and wind patterns of TOI 700 d may be strikingly different from that of the Earth. In order to predict more about the composition and potential geography of the planet, the scientists will rely on computer modelling-based on its size.