Habitable Exoplanets Could Be Common in Our Galaxy

By Clara Moskowitz

January 6, Wired

Earth-like planets may in fact be common in the galaxy, increasing the likelihood of extraterrestrial life.

By observing the remains of smashed up asteroids around dead stars, astronomers were able to deduce their chemical composition. They found that the dust of many chewed-up asteroids resembles the materials inside Earth and the other small, rocky inner planets of our solar system.

"We found evidence that this asteroid dust is similar to rocks on Earth," said UCLA astronomer Michael Jura in a press conference today at the American Astronomical Society meeting in Long Beach, California. "This strengthens suspicions that Earth-like planets are common."

Asteroids and planets are made from the same stuff: the dusty material that circles around
young stars in disks. Eventually some of the dust clumps together and grows into planets, while asteroids represent the detritus left over. Because asteroids are formed from the same material as planets, observing asteroids around other stars can tell us crucial information about what ingredients are available to form planets around those stars.

"Asteroids are leftover building blocks that didn’t get incorporated into the planets," Jura said. "What we have now is a tool to measure the bulk composition of planets."

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