More planets discovered outside solar system

This artist rendering shows planets found recently. The discovery boosts a theory that life could develop elsewhere. This artist rendering shows planets found recently. The discovery boosts a theory that life could develop elsewhere. (Associated Press/ European South Observatory)
By Seth Borenstein
Associated Press / October 20, 2009

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WASHINGTON - European astronomers have found 32 new planets outside our solar system, adding evidence to the theory that the universe has many places where life could develop.

Scientists using the European Southern Observatory telescope didn’t find any planets quite the size of Earth or any that seemed habitable or even unusual. But their announcement increased the number of planets discovered outside the solar system to more than 400.

Six of the newly found planets are several times bigger than Earth, increasing the population of so-called super-Earths by more than 30 percent. Most planets discovered so far are far bigger, Jupiter-sized or even larger.

Two of the newly discovered planets were as small as five times the size of Earth and one was up to five times larger than Jupiter.

Astronomer Stephane Udry of the University of Geneva said the results support the theory that planet formation is common, especially around the most common types of stars.

“I’m pretty confident that there are Earth-like planets everywhere,’’ Udry said. “Nature doesn’t like a vacuum. If there is space to put a planet there, there will be a planet there.’’

What astronomers called especially exciting is that about 40 percent of sun-like stars have planets that are closer to being Earth-sized than the size of Jupiter. Jupiter’s mass is more than 300 times that of Earth’s.

Depending on definitions of the size of super-Earths, the discovery suggests that planets that have a mass similar to Earth’s are “extraordinarily commonplace,’’ said Alan Boss, an astronomer at the Carnegie Institution of Washington. He was not part of the European team. “The universe must indeed be crowded with habitable worlds.’’

Boss said finding 32 planets at once is a record “and it really shows that the Europeans have taken the lead’’ in finding planets outside the solar system.

The discoveries were made by a spectrograph known as the High Accuracy Radial Velocity Planet Searcher. The instrument is an attachment to the European observatory telescope in Chile that looks for slight wobbles in a star’s movements. Those changes would be made by the tug of a planet’s gravity on the star.

There are no photos of the new planets, which are called exoplanets because they orbit distant stars. The first exoplanet was found in 1995.

The astronomers from the European Southern Observatory studied about 2,000 stars with the spectrograph, which measures the slight change in starlight caused by an orbiting planet that cannot be seen directly.

Udry said a new instrument under development, known as Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (Espresso), “should allow us to detect Earth twins around solar-type stars, within five to 10 years.’’

Also yesterday, the US Geological Survey announced that scientists have discovered a series of caves on Mars that might hold evidence of life and could provide shelter to future explorers.

The caves are believed to have been formed when lava cooled and solidified on top of channels created during ancient volcanic eruptions, making tunnels, the agency said.