IMAGE: European Southern Observatory Click for larger image of this artist rendition. After more than four years of observations using the most successful low-mass-exoplanet hunter in the world, the HARPS spectrograph attached to the 3.6-metre ESO telescope at La Silla, Chile, astronomers have discovered in this system the lightest exoplanet found so far: Gliese 581 e (foreground) is only about twice the mass of our Earth. The Gliese 581 planetary system now has four known planets, with masses of about 1.9 (planet e, left in the foreground), 16 (planet b, nearest to the star), 5 (planet c, centre), and 7 Earth-masses (planet d, with the bluish color). The planet furthest out, Gliese 581 d, orbits its host star in 66.8 days, while Gliese 581 e completes its orbit in 3.15 days.
From RedOrbit and Science News Astronomers Discover Lightest Exoplanet Yet
Astronomers claim to have discovered an exoplanet that is the most similar to Earth in terms of mass than any previously discovered.
Found in the constellation Libra, the planet known as Gliese 581 represents about twice the mass of Earth.
Astronomers have previously identified some 300 exoplanets, but most are much larger than Earth.
“This is by far the smallest planet that’s ever been detected,” said Michael Mayor, from the Geneva Observatory, Switzerland.
“This is just one more step in the search for the twin of the Earth.
“At the beginning, we discovered Jupiter-like planets several hundred times the mass of the Earth; and now we have the sensitivity with new instruments to detect very small planets very close to that of the Earth,” he told BBC News.
Mayor worked alongside an international team of scientists who made the observation using the low-mass-exoplanet hunting device known as the HARPS spectrograph, which is attached to the 3.6 meter ESO telescope at La Silla, Chile.
“The holy grail of current exoplanet research is the detection of a rocky, Earth-like planet in the ‘habitable zone’ – a region around the host star with the right conditions for water to be liquid on a planet’s surface,” Mayor said in a statement. Read the rest of this entry »
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