3 Earth-like planets have been discovered by astronomers that might be in the “habitable zone” of a small star. The planets raise the possibility that the 3 Earth-like trio have liquid water, a pre-requisite for life.
The star, known as TRAPPIST-1, is only slightly larger than Jupiter, Detroit Free Press reports. But it’s only 38.8 light years from Earth, which is relatively close. Some “exoplanets” are more than 13,000 light years away.
The 3 Earth-like planets discovery in constellation Aquarius involves planets that might be just the right distance from their host star to have surface water. Fewer than 40 of these so-called “Goldilocks” worlds are known to exist.
Advances in technology have enabled scientists to find about 2,000 planets beyond our solar system since the 1990s, and there’s some evidence for roughly 4,700 more, the Business Insider reported.
This also is the first time that scientists have found planets orbiting a comparatively small, faint object known as ultracool dwarf star, according to an international research team that includes UC San Diego, NASA, the University of Liege in Belgium and other institutions. The team reported its findings Monday in the journal Nature.
“This is almost certainly the first of many planets (that will) be found around these cool stars, because up to now their faintness made it risky to invest time and resources to monitor large numbers of them,” said Adam Burgasser, a UC San Diego astronomer who led the group that characterized TRAPPIST-1.
“The kind of planets we’ve found are very exciting from the perspective of searching for life in the universe beyond Earth.”
The 3 Earth-like planets were found using a variety of methods. One involves looking for stars that wobble a bit. The wobble can be produced by the gravitational influence of a planet that’s hidden by the glare of the star.
But the most common technique involves using a telescope to study whether a star’s brightness briefly dips. Those dips can be caused by a planet passing in front of the star, as seen from Earth. That is how scientists found the three planets in Aquarius. The phenomenon was observed late last year from La Silla Observatory in Chile.
Subsequent work with larger telescopes revealed that the planets appear to be roughly the size of Earth. The planet closest to the star completes an orbit every 1.5 days. The second does so in 2.4 days. The speed of the third, outer planet, has yet to be clearly determined, but may have an orbital period that lasts up to 73 days.
The research team was led by Michael Gillon of the University of Liege, who said in a statement, “With such short orbital periods, the planets are between 20 and 100 times closer to their star than the Earth to the Sun. The structure of this planetary system is much more similar in scale to the system of Jupiter’s moons than to that of the Solar System.”
The Discover Magazine said the 3 Earth-like planets “puts them just inside the habitable zone for this system, an orbital ring of distances at which surface water is likely to be liquid and life as we know it most likely.