TOI 700 d – a near-Earth-sized Exoplanet

TOI 700 d is a near-Earth exoplanet, most likely rocky, that orbits the red dwarf TOI 700, the system’s outermost planet. It’s a super-Earth exoplanet orbiting an M-type star. It is approximately 101.4 light-years (31.1 parsecs) from Earth in the constellation Dorado. It has a mass of 1.57 Earths, takes 37.4 days to complete one orbit around its star, and is 0.1633 AU away. TOI 700 d is one of only a few Earth-size planets discovered so far in a star’s habitable zone.

NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-sized planet in its star’s habitable zone, which is the range of distances where conditions may be just right for the presence of liquid water on the surface. Scientists used NASA’s Spitzer Space Telescope to confirm the discovery, dubbed TOI 700 d, and modeled the planet’s potential environments to help inform future observations.

It was discovered in 2020, and its discovery was announced. The Transiting Exoplanet Survey Satellite discovered it in early January 2020. (TESS). The exoplanet is the first Earth-sized exoplanet discovered in the habitable zone by the TESS.

TOI 700 b is almost exactly the size of Earth, is most likely rocky, and completes an orbit every 10 days. The middle planet, TOI 700 c, is 2.6 times larger than Earth and orbits every 16 days. It is most likely a gas-dominated world. TOI 700 d, the system’s outermost known planet and the only one in the habitable zone, is 20% larger than Earth, orbits its star every 37 days, and receives 86 percent of the energy that the Sun provides to Earth. All of the planets are thought to be tidally locked to their star, which means they rotate once per orbit so that one side is always lit up.

Physical characteristics

Mass, radius, and temperature

TOI 700 d is an Earth-sized exoplanet with a radius and mass similar to our planet. It is estimated to have a mass of around 1.72 M🜨 and a radius of about 1.19 R🜨. If it has an atmosphere similar to Earth, its average temperature would be around 268.8 K (4.3 °C; 24.2 °F). There is a slight possibility of a runaway greenhouse effect.

Host star

TOI 700 is a red dwarf of spectral class M that is roughly 40% the mass, 40% the radius, and roughly 50% the temperature of the Sun. The star is bright, but there is little stellar activity. The star does not show a single white-light flare in the 11 sectors observed with TESS. The low rotation rate also indicates a lack of stellar activity.


Every 37.4260 days, TOI 700 d orbits its host star. It orbits its star at 0.163 AU (24,400,000 km; 15,200,000 mi) from its host star with an orbital period of approximately 37.4 days, has a mass of 1.69x that of Earth, and a radius of approximately 1.19 times that of Earth. According to estimates, the planet receives approximately 86 percent of the energy that the Earth receives from the Sun.