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Earth-sized planet in ‘habitable zone’ discovered

NASA announced on Monday that its TESS satellite and ‘planet hunter’ has made it possible to discover a new planet the size of Earth and at a distance neither too close nor too far from its star, making it possible the planet may have liquid water.

The planet has been named “TOI 700 d” and at a hundred light year away is relatively close to planet Earth, Nasa announced.

“TESS was designed and launched specifically to find planets the size of Earth and orbiting nearby stars,” says Paul Hertz, director of the NASA astrophysics division.

The planet was nearly missed by TESS, but several amateur astronomers – including Alton Spencer, a young high school student – discovered an initial classification error, which helped NASA. The discovery of “TOI 700 d” was then confirmed by the Spitzer space telescope.

NASA’s TESS satellite

A few other similar planets have been discovered before, notably by the old Kepler space telescope, but this is the first by the TESS satellite, launched in 2018.

TESS focused on parts of the space to detect if objects – planets – pass in front of stars, which causes a temporary decrease in brightness of the star. This allows TESS to identify the presence of a planet, its size, its orbit, etc. The TOI 700 star is small, about 40% the size and mass of our Sun, with a surface temperature that is less than half.

TESS discovered three planets orbiting this star, which have been named TOI 700 b, c, and d. Only “d” is in the so-called “habitable zone”. The planet is almost the size of the Earth (20% larger), and circles its star in only 37 days.

It remains to be seen what the planet is made of. Researchers have generated models based on the size and type of the star, in order to predict the composition of its atmosphere and the planet’s surface temperature.

The Brussels Times