NASA detects Earth-size planet just 40 light-years away that's 'not a bad place' to hunt for life

Scientists using a NASA space telescope have discovered a tantalizing world. It's about the size of Earth, sits remarkably close to our solar system, and could be comfortable for life as we know it.

The extrasolar planet, or "exoplanet," named Gliese 12 b, orbits a small and cool red dwarf star located just around 40 light-years from Earth in the constellation Pisces. The exoplanet — which the team found with NASA's Transiting Exoplanet Survey Satellite (TESS) — is estimated to have a width around 1.1 times that of Earth, making it similar to our planet as well as Venus, which is often called our world's solar system "twin."

Gliese 12 b orbits its star, Gliese 12, so closely that its year lasts just 12.8 Earth days. However, because the red dwarf Gliese 12 is just around a quarter of the size of the sun, it is also much cooler than our star. This means that, even though Gliese 12 b is at a distance from its red dwarf parent equivalent to just 7% of the distance between the sun and Earth, it still is in its planetary system's habitable zone. Also known as the "Goldilocks Zone," the habitable zone is the region around a star that is neither too hot nor too cold for planets to host liquid water, a vital ingredient for life as we know it. Though, importantly, the two teams behind the discovery of Gliese 12 b can't yet say for sure if it has an atmosphere. It therefore remains unclear if the world could be habitable, but the researchers have some cautious optimism.

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"The majorly interesting thing is that this is a planet that's really nearby; in fact, it's one of the closest transiting planets to Earth," University College of London scientist Larissa Palethorpe, who co-led the research with University of Southern Queensland astrophysicist Shishir Dholakia, told Space.com. "It's either in the habitable zone of its star or it is right on the edge of it — so, it could be habitable."

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Scientists spotted Gliese 12 b as it crossed, or "transited," the face of its parent red dwarf star. These transits cause tiny dips in light that TESS is adept at spotting. Palethorpe added that, when the team went into this project, they didn't know what the orbital period or the size of the planet would be for sure. 

"To find it to be such a similar size to Earth was kind of a lovely surprise," she continued. "So that was a really nice thing to be able to nail down, but I think especially knowing that, in terms of habitability, it could lie between Earth and Venus, is really exciting."