Earth-like planet ’may not exist’: Goldilocks just a fairytale?
Source: dailymail.co.uk
Its discovery last month captured the imaginations of millions around the globe.And the news that an Earth-like planet had been found which could support life and which lay only 20 light years away sparked feverish speculation that we may not be alone in the universe.
But now a group of scientists have claimed that Gliese 581g, a rocky world just three times the size of Earth, may not even exist.
The devastating claim has been made by a group of Swiss astronomers who have cast doubt on the original research and say that they can find no trace of the planet in their own analysis of the same data.
This artist’s conception shows the inner four planets of the Gliese 581 system and their host star, a red dwarf star only 20 light years away from Earth. The four tiny planets in the background are the planets that have already been discovered. The closer, blue and green planet is 581G, the most Earth-like planet ever discovered.
In the original announcement last month a team led by Dr Stephen Vogt from the University of California said that Gliese 581g lay in its star’s ’Goldilocks zone’ - the region in space where conditions are neither too hot or too cold for liquid water to form oceans, lakes and rivers.
Planets orbiting distant stars are too small to be seen by telescopes. Instead, astronomers look for tell-tale gravitational wobbles in the stars that show a planet is in orbit.
But Francesco Pepe of the Geneva Observatory in Sauverny, Switzerland, told a conference in Torino, Italy, that a combination of old and new data acquired by his team shows no sign of the planet.
Pepe said: ’If a signal corresponding to the announced Gliese 581g planet was present in our data we should have been able to detect it.’
His team had access to the same sets of data that the original researchers who trumpeted the existence of the planet to worldwide fanfare at the end of September.
Those measurements revealed a total of four planets circling the star. The team’s latest report also includes an additional 60 measurements made with the sensitive HARPS spectrograph on a telescope at La Silla, Chile.
They discovered the existence of the four planets circling Gliese 581, which had already been confirmed, but could find no sign of Gliese 581g - the planet which had gripped the public’s imagination.
Pepe told the conference: ’From these data we easily recover the four previously announced planets. However, we do not see any evidence for a fifth planet in an orbit of 37 days’.
He told New Scientist that he was not trying to undermine Dr Steven Vogt who led the original study at the University of California, Santa Cruz.
’We are not trying to prove the nonexistence of a planet,’ Pepe said. ’It’s really difficult to prove that something does not exist. We are just saying we do not see a significant signal that is really different from noise.’
Steven Vogt, who did not attend the meeting in Turin, told New Scientist said that HIRES data – which were not used by the Geneva team – were needed in order to see the planet.
The orbits of planets in the Gliese 581 system are compared to those of our own solar system. The Gliese 581 star has about 30% the mass of our sun, and the outermost planet is closer to its star than we are to the sun. The 4th planet, G, is a planet that could sustain life.
He told the magazine: ’I feel confident that we have accurately and honestly reported our uncertainties and done a thorough and responsible job extracting what information this data set has to offer.’
He added: ’In 15 years of exoplanet hunting, with over hundreds of planets detected by our team, we have yet to publish a single false claim, retraction, or erratum.’
The Swiss team has not yet published its results in a peer-reviewed journal - crucial if its doubts are to be taken seriously by the scientific community.
Last month researchers said that the discovery of Gliese 581g suggested the universe is teeming with world like our own.
If it exists, it is so far away, spaceships travelling close to the speed of light would take 20 years to make the journey. If a rocket was one day able to travel at a tenth of the speed of light, it would take 200 years to make the journey.
The findings come from 11 years of observations at the W. M. Keck Observatory in Hawaii.
The planet orbits a small red star called Gliese 581 in the constellation of Libra. The planet, named Glieseg, is 118,000,000,000,000 miles away - so far away that light from its start takes 20 years to reach the Earth.
It takes just 37 days to orbit its sun which means its seasons last for just a few days. One side of the planet always faces its star and basks in perpetual daylight, while the other is in perpetual darkness.
The most suitable place for life or future human colonists would be in the ’grey’ zone - the band between darkness and light that circles the planet.
’Any emerging life forms would have a wide range of stable climates to choose from and to evolve around, depending on their longitude,’ said Dr Vogt who reported the find in the Astrophysical Journal.
Astronomers have now found six planets in orbit around Gliese 581 - including the no-disputed ’g’ - the most discovered in a planetary system other than our own solar system.
Its star is a red giant - a massive star near the end of its life. It is too dim to see in the night sky from Earth without a telescope.
Astronomers have found nearly 500 exoplanets - or planets outside our own solar system.
However, almost all are too big, made of gas instead of rock, too hot or too cold for life as we know it.
Article from: dailymail.co.uk
Ed Note: So, they discovered the planet, assured us it would contain "life", detected strange light pulses coming from it, and now it doesn’t exist? Hmmm....
~E
