An artist"s explicate of a rocky, Earth-size exoplanet.(Image credit: NASA Ames/SETI Institute/JPL-Caltech)
On Earth, over there is life virtually almost everywhere there is liquid water. As such, the hunt because that extraterrestrial life has concentrated on so-called habitable or "Goldilocks" zones — areas approximately stars temperate sufficient for planets come possess liquid water on their surfaces.

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Since planet is the only inhabited human being known, this world is normally the focus of research studies on habitability. However, scientists have actually reasoned that people other 보다 Earth-like ones might offer conditions suitable for life to emerge and evolve. Such civilizations might also prove "super-habitable," or have better chances in ~ hosting life than Earth.

"We room so over-focused on detect a mirror picture of earth that we might overlook a world that is even more well-suited for life," examine lead author Dirk Schulze-Makuch, one astrobiologist in ~ Washington State college in Pullman and also the technological University that Berlin, said

Related: 10 exoplanets that could host extraterrestrial life

Potential havens for life

To find for potentially super-habitable exoplanets, researcher investigated the Kepler object of interest Exoplanet Archive, focusing on 4,500 planetary solution that most likely possessed rocky planets within your stars" habitable zones.

In enhancement to looking in ~ planetary equipment with yellow dwarf stars prefer our sun, the scientists also looked in ~ orange dwarf stars, i m sorry are somewhat cooler, dimmer and also less enormous than our sun. Whereas ours sun has a lifetime approximated at less than 10 exchange rate years, orange dwarfs have lifetimes of 20 billion to 70 exchange rate years. Since facility life took about 3.5 billion years to show up on Earth, the much longer lifetimes that orange dwarfs might give planets within their habitable zones more time to develop life and accrue biodiversity. Orange dwarfs are also around 50% more frequent than yellow dwarfs in the Milky Way.

"Our sun is actually no the finest kind the star for hosting a earth with several life on it," Schulze-Makuch said.

An larger planet might give life much more time to evolve. Planet is about 4.5 billion years old, therefore the researchers speculated the sweet spot because that life is a world that is between 5 billion to 8 billion years old.

The size and mass of a earth can also influence just how well it deserve to support life. A world that is 10% more comprehensive than earth would have much more habitable land. One that is about 1.5 times Earth"s mass would certainly be expected to maintain its interior warm longer, which consequently would help keep its main point molten and also its safety magnetic areas active. A heavier earth would additionally have more powerful gravity to aid retain its atmosphere over a longer expectancy of time.

Worlds that are slightly warmer than earth by around 8 levels Fahrenheit (5 degrees Celsius) could be super-habitable, since they can have bigger tropical zones that might be an ext benign for an ext biodiversity. However, warmer planets might also need more moisture, because greater heat can expand deserts.

In addition, planets through the very same amount of floor area as earth but broken up right into smaller continents could be much more habitable. Once it concerns continents that too huge (such together Earth"s past continent Gondwana about 500 million year ago), your centers are far from oceans, frequently rendering the interiors of big continents vast, unwelcoming deserts. Moreover, Earth’s shallow waters have actually a better biodiversity 보다 its deep oceans, therefore planets v shallower waters might be super-habitable.

Super-habitable haul

All in all, the scientists determined 24 possibly super-habitable planets. None met all the criteria the researchers attracted up because that super-habitable planets, yet one did satisfy at least two — KOI 5715.01, a planet around 5.5 billion year old and also 1.8 to 2.4 times Earth"s diameter orbiting an orange dwarf around 2,965 light-years away. It could have an average surface temperature about 4.3 levels F (2.4 degrees C) cooler than Earth, yet if that has more greenhouse gases than planet to catch heat, it could be super-habitable, they said.

Schulze-Makuch"s favorite possibly super-habitable people from this 24 to be KOI 5554.01, a world around 6.5 billion year old 0.72 come 1.29 times Earth"s diameter orbiting a yellow dwarf about 700 light-years from Earth.

"I really liked the median surface temperature — about 27 degrees C <80 levels F>," Schulze-Makuch said. "And it"s probably around Earth"s size, and a little bit older 보다 Earth."

All 24 of these perhaps super-habitable planets are an ext than 100 light-years native Earth. This provides them too much for NASA"s Transiting Exoplanet survey Satellite (TESS) audioeditorfree.comcraft to record high-quality pictures from to learn an ext about them.

Still, Schulze-Makuch listed that future audioeditorfree.comcraft, such as NASA"s James Webb Telescope, NASA"s LUVIOR observatory and the European room Agency"s PLATO an are telescope, could shed light on these worlds.

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"We caution the while we find for super-habitable planets, that doesn"t typical that they have to contain life," Schulze-Makuch said. "A planet deserve to be habitable or super-habitable however uninhabited."

The scientists in-depth their findings online Sept. 18 in the newspaper Astrobiology.

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Charles Q. Choi is a contributing writer for and Live Science. He covers every things human origins and also astronomy and also physics, animals and also general scientific research topics. Charles has actually a understand of Arts level from the university of Missouri-Columbia, college of Journalism and also a Bachelor of Arts degree from the university of southern Florida. Charles has actually visited every continent on Earth, drink rancid yak butter tea in Lhasa, snorkeling with sea lions in the Galapagos and also even rise an iceberg in Antarctica. Visit him in ~