Ever wondered if there is life somewhere beyond planet earth? A recent discovery gives some hope to the idea that there may just be another planet capable of harboring life out beyond our solar system.
After 11 years of data collection, a team of astronomers led by Steven Vogt of the University of California Santa Cruz and Paul Butler of the Carnegie Institute have identified a planet that might just have the right conditions for life to exist.
By observing the “wobbling” of the parent star, Gliese 581, astronomers have been able to identify a number of planets, the most recent and significant being Gliese 581g. Their work will soon be published in The Astrophysical Journal.
The parent star, Gliese 581, is a red dwarf located about 20 light years away from Earth, visible in the night sky among the stars that form the constellation Libra.
Red dwarfs such as Gliese 581 emit a spectrum of electromagnetic radiation that contains mostly infrared radiation, whereas the Sun’s spectrum also contains visible and ultraviolet light. The luminosity and mass of red dwarfs are also less than that of the Sun and many other types of stars.
These characteristics of Gliese 581 establish its habitable zone, a range of stellar orbits where a planet may be able to sustain water. Gliese 581’s habitable zone is at a much shorter distance than that of other stars.
The planet Gliese 581g, at a distance of approximately 14 million miles from the star, is located well within Gliese 581’s habitable zone. Two planets previously discovered to orbit Gliese 581, Gliese 581c and Gliese 581d, are located at opposite edges of the habitable zone and were considered to have some chance of containing life, but were respectively too hot and too cold.
The astronomers relied on observations made from the Keck Observatory atop the summit of Mauna Kea on the island of Hawai’i. Focused on specific oscillations and other minute movements of Gliese 581, they looked for specific signs of any tugs or pulls caused by orbiting planets.
“Six planets are pulling the star as they orbit around it; by carefully measuring the star’s motion over the course of many years, these six components of its acceleration can be separated,” wrote Daniel Apai, Assistant Astronomer at the Space Telescope Science Institute here at Homewood, in an email with The News-Letter.
Gliese 581g is estimated to have a mass about three to four times the size of Earth’s, and a radius as much as twice the size of Earth’s.
It is tidally locked, meaning one side of its surface constantly faces the star while the other does not, leaving the most likely habitable region lying along an equator where the dark and the light sides of the planet meet. The planet orbits Gliese 581 once every 37 Earth days.
More certain confirmation of the possibility of life on Gliese 581g is still many years away, as information about surface conditions and the existence of an atmosphere are needed. Although not affiliated with the discovery of the planet, Apai is familiar with the information needed to confirm the presence and chemical makeup of an atmosphere.
According to Apai, this will require new equipment that is able to detect much fainter sources of light apart from much brighter sources.
“We would need a very large space telescope that is capable of separating the dim light of the planet from the extremely bright light of its host star: something that is much larger and more powerful than the Hubble Space Telescope,” he wrote.
There are, however, plans in the works to develop such a telescope.
“While technically challenging, building such a machine is possible; plans for such a powerful telescope (“Terrestrial Planet Finder”) have been proposed to NASA and will probably become reality in a decade or two,” he wrote.
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