Astronomers have found at least seven Earth-sized planets orbiting the same star 40 light-years away, according to a study published Wednesday in the journal Nature. The findings were also announced at a news conference at NASA headquarters in Washington.
This discovery outside of our solar system is rare because the planets have the winning combination of being similar in size to Earth and being all temperate, meaning they could have water on their surfaces and potentially support life, CNN reported.
The seven exoplanets were all found in tight formation around an ultracool dwarf star called TRAPPIST-1. Estimates of their mass also indicate that they are rocky planets, rather than being gaseous like Jupiter. Three planets are in the habitable zone of the star, known as TRAPPIST-1e, f and g, and may even have oceans on the surface.
The researchers believe that TRAPPIST-1f in particular is the best candidate for supporting life. It’s a bit cooler than Earth, but could be suitable with the right atmosphere and enough greenhouse gases.
The planets are so close to each other and the star that there are seven of them within a space five times smaller than the distance from Mercury to our sun. This proximity allows the researchers to study the planets in depth as well, gaining insight about planetary systems other than our own.
Starting closest to the star and moving out, the planets have respective orbits from one and a half to nearly 13 Earth days. The orbit of the farthest planet is still unknown.
Based on preliminary climate modeling, the researchers believe that the three planets closest to the star may be too warm to support liquid water, while the outermost planet, TRAPPIST-1h, is probably too distant and cold to support water on the surface. But further observation is needed to know for sure.
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