Habitable earth-sized planet discovered but its Sun doesn't set for over two weeks

• The National Aeronautics and Space Agency has discovered an Earth-sized planet 100 lightyears away with the potential to support human life.
• The planet, TOI 700 d, has the right conditions to allow the presence of liquid water on its surface.
• Its star is 40% the size of our Sun and only half as hot.

The Earth isn’t going to last forever. Scientists continue to debate over what poses the greater threat to humanity — World War III, global warming, or overpopulation — but most agree that the planet’s demise is inevitable.

That is why space agencies all over the world are looking for other planets that could support human life. The National Aeronautics and Space Agency (NASA) seems to have found one — TOI 700 d, an Earth-sized just over 100 lightyears away.

This means that the planet’s conditions are suitable to allow the presence of liquid water on the surface.

Not only is it one of the few planets capable of supporting human life, but it’s also the Transiting Exoplanet Survey Satellite’s (TESS) — NASA’s ‘planet hunter’ — first discovery of a habitable-zone.

The scope for human life 100 lightyears away

TOI 700 d is located in the Dorado constellation orbiting a cool M dwarf star — and it’s not alone. Two other planets also orbit the same Sun. TOI 700 b is the innermost planet of the system. It’s also Earth-sized and believed to have a rocky surface. Since it’s so close to the star, it only takes the planet 10 days to complete one orbit.


TOI 700 c, the middle planet, is more than twice the size of Earth and believed to be largely dominated by gas. It takes around 16 days to complete its orbit.

TOI 700 d is only one suited for human habitation. The energy is received for its star is around 86% of the energy the Earth receives from the Sun. It’s tidally locked in orbit, which means it only rotates once as it goes around its star. And, one orbit takes 37 days.

This means, on average, daylight would persist on side of the planet for at least 15 days at a single stretch.

TOI 700 d’s star

TOI 700, the star at the centre of this planetary system, was originally classified as being the same as the Sun. Only later, did astronomers discover that TOI 700 only has 40% of the Sun’s mass and size — and is only half as hot.


"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," said Emily Gilbert, a graduate student at the University of Chicago.

Although TESS first spotted the planet, its discovery was only confirmed after the Spitzer Space Telescope was able to verify its existence.

"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," said Paul Hertz, the director of the astrophysics division at NASA.

TOI 700 d isn’t the only planet in the universe that has the potential to support human life. NASA’s Kepler Space Telescope has identified several other planets that could allow for water on their surface. But, without more data, it will be difficult to discern if there are other obstacles to prevent human habitation.

See also:
NASA's planet-hunter uncovers its first world with two stars 1,300 light-years away

Space race heads to Mars — Four missions plan to explore Earth's closest neighbour in July this year

Indian scientists spot a galaxy 260 light-years away that isn't giving birth to any new stars