As many as 60% of Sun-like stars in the Milky Way may form rocky planets similar to Earth, according to recent findings from NASA's Spitzer Space Telescope. The findings suggest that other worlds with potential for life might be more common than previously thought.
Astronomers used the infrared telescope to look for signs of warm dust around 309 distant stars grouped together by age.
They found that younger stars -10 to 20 million years old - had dust around them at temperatures suggesting the dust disks lay at distances from the stars where planets would be likely to form. The farther away from a star the dust lies, the colder it gets.
"We detect the heat radiation of dust grains," says Michael Meyer of the University of Arizona, Tucson. "From those observations, we infer the presence of colliding larger rocky bodies that bang together and generate dust."
He presented the findings at the American Association for the Advancement of Science conference in Boston, US, on Sunday.
The dust grew less abundant as they looked at older stars until it disappeared almost entirely around stars that were 300 million years old or older, suggesting that the dust is likely to have been accreted into the form of planets. The time frame corresponds to the time it is likely to have taken for Earth and other planets in our solar system to form through the collision of smaller bodies. The amount of dust found around different ages of stars suggests that between 20-60% of stars similar to the Sun are candidates for forming terrestrial planets.
Astronomers now know of more than 250 extra-solar planets and many more are likely to be uncovered when the Kepler Space Observatory launches in 2009.
Alan Stern, a planetary scientist at NASA, says 1000 or more additional planetary bodies may be lurking at the outermost edges of our solar system, in the mysterious band of icy debris beyond Neptune called the Kuiper Belt, and in the more distant Oort Cloud, where some comets are believed to originate.
"If you like change hold on to your hat, because the view of our solar system is changing dramatically," says Stern. "I fully expect in the deep outer solar system that we will find objects the size of Earth, Mars and potentially larger as this century unfolds."
By Edward
Fri Feb 22 07:17:57 GMT 2008
It seems that, in the universe, life is not the exception but the norm. The more I read about astronomy, the more I am getting the message that the universe is like a nursery for living things! The pity is, that technology and science haven't produced a method to do direct studies of alien planetary systems.All comments should respect the New Scientist House Rules. If you think a particular comment breaks these rules then please use the "Report" link in that comment to report it to us.
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