The planet, dubbed TOI 700 d, was discovered by NASA’s TESS satellite, and is one of only a few Earth-sized planets discovered in a star’s habitable zone so far
NASA has discovered a new Earth-sized planet that could be home to aliens .
The planet, dubbed TOI 700 d, was discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS), and is one of only a few Earth-sized planets discovered in a star’s habitable zone so far.
Paul Hertz, astrophysics division director at NASA Headquarters in Washington, said: “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.”
The planet orbits a small, cool M dwarf star called TOI 700, which is located just over 100 lightyears away from Earth.
The star is roughly 40% of the Sun’s mass and size, and about half its surface temperature.
Several planets appear to orbit the star. The innermost planet, TOI 700 b, is a rocky planet that’s almost exactly the same size as Earth, while the middle planet, TOI 700 c, is 2.6 times larger than Earth, and is a gas-dominated world.
Finally, the outermost planet, TOI 700 d, is the only one in the habitable zone, and is around 20% larger than Earth.
To confirm the planets’ sizes and compositions, NASA used its Spitzer Space Telescope.
Joseph Rodriguez, an astronomer at the Centre for Astrophysics Harvard & Smithsonian, said: “Given the impact of this discovery – that it is TESS’s first habitable-zone Earth-size planet – we really wanted our understanding of this system to be as concrete as possible.
”Spitzer saw TOI 700 d transit exactly when we expected it to. It’s a great addition to the legacy of a mission that helped confirm two of the TRAPPIST-1 planets and identify five more.”
While TOI 700 d’s exact conditions are unknown, the researchers used 3D climate models to predict its surface type and atmospheric composition.
One model suggests that the planet may be ocean-covered with a dense, carbon-dioxide-dominated atmosphere, while another indicates that TOI 700 d could be an all-land version of modern Earth.
The researchers hope that further data on the planet will help to work out which of these models is correct.
Gabrielle Englemann-Suissa, a Universities Space Research Association visiting research assistant at Goddard, added: “Someday, when we have real spectra from TOI 700 d, we can backtrack, match them to the closest simulated spectrum, and then match that to a model.
“It’s exciting because no matter what we find out about the planet, it’s going to look completely different from what we have here on Earth.”