In my opinion the new discovery is simply amazing but I wouldn't send the workaholics I mentioned in my previous post to this planet. It makes you wonder if there really is life on other planets and if there is what kind of creatures live there? Where did those creatures come from? Where do WE come from?
Earth-like planet discovery 'may support life'
25/04/2007 - 07:51:11
An Earth-like planet that could be covered in oceans and may support life has been discovered outside the Solar System.
The new world, which is 20.5 light years away, orbits a region with the right temperature to allow liquid water on its surface.
Scientists believe it is only 1.5 times larger and five times more massive than Earth, making it the smallest extra-solar planet known.
But the really exciting discovery is that the planet inhabits the habitable zone of its parent star, Gliese 581.
Also known as the “Goldilocks zone”, this is the narrow orbit in which temperatures are not too hot, not too cold, but just right for surface water to exist as a liquid.
The habitable zone varies according to the heat output of the star, and Gliese 581 is much smaller and colder than the Sun. So even though the planet is 14 times closer to the star than the Earth is to the Sun, it lies in a region where rivers, lakes and oceans are possible.
Liquid water is one of the pre-requisites for life as we know it on Earth.
Dr Stephane Udry, from the Geneva Observatory in Switzerland, who led the European astronomers who announced the find today, said: “We have estimated that the mean temperature of this super-Earth lies between zero and 40 degrees Celsius, and water would thus be liquid.
“Moreover, its radius should be only 1.5 times the Earth’s radius, and models predict that the planet should be either rocky – like our Earth – or covered with oceans.”
The vast majority of planets already discovered orbiting stars outside the Solar System are giant gaseous worlds the size of Jupiter or bigger.
Life as we know it could not exist on these planets. But the new planet is highly unusual because it is so small, and therefore probably rocky. Given its size and location, it is also likely to have an atmosphere.
Two other planets also orbit Gliese 581, which lies in the constellation of Libra and is among the 100 closest stars to the Sun.
One, Gliese 581 B, discovered two years ago, is a Neptune-like planet with 15 Earth-masses so close to the star that it makes an orbit every 5.4 days. The other, Gliese 581 D, has eight times the Earth’s mass and completes an orbit in 84 days. The new planet, with a 13-day orbit, is designated Gliese 581 C, but as yet has no name.
The planet was found by Swiss, French and Portuguese astronomers using the European Southern Observatory’s 3.6 metre telescope at La Silla in Chile.
They employed a method of long-distance planet finding that looks for the “wobble” on a star caused by the gravity of a large object orbiting it.
By measuring the wobble motion, shown as shifts in the star’s light spectrum, astronomers can calculate a planet’s orbit and mass.
Gliese 581 C is certain to be a key target for future missions dedicated to the search for extra-terrestrial life.
“Liquid water is critical to life as we know it,” said Dr Xavier Delfosse, a member of the team from Grenoble University in France. “On the treasure map of the universe, one would be tempted to mark this planet with an X.”
COROT, the first space telescope specifically designed to search for Earth-like rocky planets around stars other than the Sun, was launched by the European Space Agency (ESA) last December.
By 2020 at least one space telescope should be in orbit with the capability of detecting signs of life on planets light years from Earth.
Two such missions, Darwin and the Terrestrial Planet Finder, are planned by ESA and the American space agency Nasa.
Both craft will have instruments sensitive enough to spot water and oxygen on Gliese 581 C, should it exist.
Dr Malcolm Fridlund, ESA project manager for COROT and study scientist on the Darwin project, said: “This is a very important step on the road to finding Earth-like planets. The planets we’ve found so far outside the Solar System have all been different from our own Earth, and more like Jupiter or Neptune.
“If this is a rocky planet it’s very likely that it will have liquid water on its surface, which means there may also be life.
“There are caveats, one being that the environment around a red dwarf is very full of radiation. All red dwarfs have a lot of flare activity, but this doesn’t necessarily exclude life.”
Scientists have calculated that the planet has about double Earth’s gravity. Any creatures living there would therefore be twice as heavy as they would be on Earth.
Their bodies would probably reflect this, said Dr Fridlund. Weak, fragile animals would not be able to support themselves or move around on land.
“Life on Earth evolved to fit the environment through natural selection,” Dr Fridlund added. “With a big pressure you would need a strong skeleton, or shell, or to be soft and malleable.”
Since Gliese 581 is much older than the Sun, life on the planet may have existed for longer than it has on Earth. Tantalisingly, it could therefore be more advanced.
Scientists at the SETI (Search for Extra-Terrestrial Life) Institute in the US are understood to be taking the possibility seriously and turning their radio telescopes towards the planet.
A paper on the discovery has been submitted to the journal Astronomy and Astrophysics.
SETI has already listened for intelligent signals from Gliese 581 on two occasions in 1995 and 1997, as part of a general sweep of stars within 45 light years of Earth.
Spokesman Dr Seth Shostak confirmed that SETI would be tuning in to the star again, using its new Allen telescope array in the Cascade Mountains of north east California.
The Allen array is still under construction but the first 42 of its 350 antennae should be ready for use this summer.
“We’ll be taking another look,” said Dr Shostak. “I suspect it will move to the top of the list.
“I am excited about this discovery. We have assumed all along that small planets will exist in great numbers, and some by chance will be in the habitable zone. But we haven’t been able to find them because the instruments favour big planets.”
He added that having an old star increased the likelihood of intelligent life.
“Life on Earth is four billion years old, and it’s taken all of that to produce us,” he said. “The older the star is, maybe the greater the chance that it has produced something that’s clever.”
Aliens living on the planet would be able to pick up 20-year-old TV and radio transmissions from Earth if they had a receiver powerful enough, he said, but it would be easier for them to detect military radar signals.
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