On 29 September 2010 a team of astronomers announced the discovery of an Earth-sized exoplanet Gliese 581g in the habitable (‘Goldilocks’) zone of a nearby red dwarf star. The planet has a mass three to four times that of the Earth, which suggests that it is probably a rocky planet with enough gravity to hold on to an atmosphere. Altogether the findings could make Gliese 581g the most Earth-like exoplanet yet found, and the strongest contender so far for a potentially habitable planet – one that could sustain life.
Gliese 581g is tidally locked to its host star, with one side always facing the star in perpetual daylight. The most habitable zone on the planet would be the ‘terminator’ – the line between shadow (night) and light (day).
The host star, Gliese 581, is located 20.5 light years from Earth in the constellation Libra. Among the six planets so far discovered orbiting the star, two others (planets c and d) lie at the edges of the habitable zone, and some astronomers still think planet d may be habitable if it has a thick enough atmosphere.
The new findings have been made by the Lick-Carnegie Exoplanet Survey, led by Steven Vogt (University of California, Santa Cruz) and Paul Butler (Carnegie Institute, Washington). They are based on 11 years of observations of Gliese 581 at the W.M. Keck Observatory in Hawaii, made using the HIRES spectrometer on the Keck I Telescope. This allows precise measurements of a star’s radial velocity, which can reveal the presence of orbiting planets whose gravitational pull causes periodic changes in the host star’s radial velocity.
The team’s findings are to be published in The Astrophysical Journal and have been posted online at arXiv.org.
Steven Vogt believes that the surprising speed with which they have been able to find a nearby star system with a potentially habitable planet means that there could be ‘tens of billions of these systems in our galaxy’.
If you’re interested in the possibility of life on other planets, join us on 14 October when the Royal Observatory, Greenwich teams up with Sci-Fi-London for a special night investigating extraterrestrial life in science,
fiction and comedy. All ticket holders will see our exclusive new
planetarium show Astrobiology and will also have the chance to sign up for a range of other activities on a first-come first-served basis including a preview screening of Gareth Edwards’ new sci-fi movie Monsters, an adventure game around the Observatory, telescope viewing and a lighthearted tour of the Observatory’s meteorite collection. Find out more
Cost: £15
Book online or call 020 8312 6608.
If you want to study life beyond Earth in more detail, why not sign up for this short course with Dr Lewis Dartnell. ‘Astrobiology’ is a brand new field of science, encompassing research
into the origins and limits of life on our own planet, and where life
might exist beyond the Earth. But what actually is ‘life’ and how did
it emerge on our own world? And where else might provide conditions
suitable for life, either in our own solar system or among the
exoplanets so far discovered?
Cost: £50
Book online or call 020 8312 6608.
No comments.