Under a septillion suns: The universe holds THREE times more stars than was previously thought
Por Fiona Macrae, em Dailymail.
The chances of alien life existing beyond the Earth have been boosted by the discovery that the number of stars in the universe might be triple current estimates.
This would potentially take the total for the universe to a stellar three septillion – or a three followed by 24 zeroes – more than the total number of grains of sandon all the Earth’s beaches and deserts.
If that were not mind-boggling enough, the discovery boosts the chances of extra-terrestrial life.
The ‘new stars’ are red dwarfs – small bundles of glowing gases cooler and dimmer than the sun.
Astronomers have discovered that dim red dwarf stars in nearby elliptical galaxies (right) are much more numerous than in our own Milky Way (left). This suggests that the total number of stars in the universe could be up to three times higher than previously thought
Astronomer Pieter van Dokkum said: ‘There are possible trillions of Earths orbiting these stars.’
They were already known to be the most abundant type of star. But our inability to ‘see’ much past our own galaxy meant no one realised just how common they were,
Professor Van Dokkum, of the prestigious Yale University in the US, used one of the world’s largest telescopes to ‘peer’ far past our own Milky Way into eight egg-shaped elliptical galaxies.
The giant telescope at the Keck Observatory in Hawaii picked out the particular pattern of light emitted by red dwarfs – and the ‘signature’ was much stronger than expected.
The elliptical galaxies were found to be home to 20 times more red dwarfs than the Milky Way. Across the universe as a whole, this could treble the number of stars, the journal Nature reports.
Professor Van Dokkum said: ‘No one knew how many of these stars there were.
‘Different theoretical models predicted a wide range of possibilities , so this answers a long-standing question about just how abundant these stars are.’
Charlie Conroy, the study’s co-author said: ‘We usually assume other galaxies look like our own. But this suggests other conditions are possible in other galaxies.’
More stars also mean more planets – raising the odds that we are not alone in the universe.
And the great age of the red dwarfs found in the elliptical galaxies raises the odds of another form of life having evolved even more, say the researchers.
Boosting the number of red dwarfs also raised the number of planets orbiting the stars – and the odds in favour of extraterrestrial life.
The red dwarfs discovered were typically more than 10 billion years old, which provides enough time for complex life to evolve.
One recently detected exoplanet astronomers believe could potentially harbour life orbits a red dwarf star called Gliese 581.
‘There are possibly trillions of Earths orbiting these stars,’ said Dr van Dokkum.
The discovery also has implications for theories about dark matter, the mysterious invisible ‘stuff’ that appears to exert a gravitational influence on galaxies but cannot be detected directly.
More abundant red dwarfs might mean that galaxies contain less dark matter than earlier measurements indicated.
Edinburgh University researchers recently calculated that almost 40,000 worlds in our galaxy are hospitable enough to be home to creatures at least as intelligent as ourselves.
Astrophysicist Duncan Forgan created a computer programme that collated all the data on several hundred planets known to man and worked out what proportion would have conditions suitable for life.
The estimate, which took into account factors such as temperature and availability of water and minerals, was then extrapolated across the Milky Way.
What is more, these lifeforms would not be mere amoeba wriggling on the end of a microscope but fully-fledged aliens, because the scientists’ definition of intelligent life is a species at least as advanced as humans.
And, as outlandish as the theory sounds, many Britons believe in little green men.
When more than 2,000 men and women were polled for the Royal Society, 44 per cent said they believe in extra-terrestrial life.
Just 28 per cent were non-believers, with the remaining 28 per cent saying they simply couldn’t be sure.