An astronomer in Hawaii speculates that newly discovered planet Gliese 581g could have liquid water on its surface.
The planet, about 30 percent larger than Earth, was discovered using one of the telescopes of the W. M. Keck Observatory on Mauna Kea. It orbits Gliese 581, 20 light-years from Earth in the constellation Libra.
"By determining the orbit of this planet, we can deduce that its surface temperature is similar to that of Earth," said University of Hawaii at Manoa's Nader Haghighipour. Given that it is tidally locked, so one part faces its sun and one side is always cold, some of any water that may exist on the surface of the planet or in its atmosphere could be in liquid form rather than ice or vapor. The discovery of liquid water in space would be an important milestone in the search for extraterrestrial life.
The team that made the discovery is led by Steven Vogt of the University of California, Santa Cruz (UCSC) and Paul Butler of the Carnegie Institution of Washington. Other team members include Haghighipour, UCSC associate research scientist Eugenio Rivera, and Gregory Henry and Michael Williamson of Tennessee State University.
The discovery team estimated that Gliese 581g has a mass three to four times that of Earth, and orbits its star in just under 37 Earth days. Its mass indicates that it is probably a rocky planet with enough gravity to hold on to its atmosphere. It is one of six known planets orbiting the star.
To discover the planet, researchers looked for the tiny changes in the star's velocity that arise from the gravitational tugs of its planets. They used 238 separate observations of Gliese 581 taken over a period of 11 years.
Haghighipour said everyone is keeping tabs on many nearby stars using the Keck Observatory. "As we collect more and more data about how these stars are moving, we expect to find many more planets with potentially Earth-like conditions," he said. He noted that to learn more about the conditions on these planets would take even bigger telescopes, such at the Thirty Meter Telescope planned for Mauna Kea.
Source: University of Hawaii at Manoa