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."
[. . .]
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.