Scientists snap first photos of planets in other solar systems

Marking a milestone in the search for Earth-like planets elsewhere in the universe, two teams of astronomers have parted the curtains of space to take the first pictures in history of planets orbiting stars other than our sun.

“This is amazing,” said Eugene Chiang, an astronomer at the University of California, Berkeley. “It’s almost science fiction. I didn’t think this day would occur until years from now.”

The first team, led by Berkeley researchers, used the Hubble Space Telescope to take a picture of a giant planet orbiting the star Fomalhaut, located 25 light-years from Earth.

Paul Kalas, the lead astronomer for the Berkeley team, said he “nearly had a heart attack” when he found the new planet, which he calls Fomalhaut b.

“It’s a profound and overwhelming experience to lay eyes on a planet never before seen,” he said.

The other effort relied on the giant Keck and Gemini telescopes in Hawaii to image three planets surrounding the young star HR8799, 130 light-years — 700 trillion miles — away. Benjamin Zuckerman, an astronomer at the University of California, Los Angeles, and a member of the Keck-Gemini team, noted that it had been only about a decade since the first exoplanet — a planet orbiting another star — was found.

Both discoveries were reported Thursday by the journal Science.

Finding other Earths has been a dream of scientists and authors for centuries. The big problem for all planet hunters is that stars other than our sun are far away, so far that their light overwhelms the weak reflected light of any nearby planets.

So far, more than 200 exoplanets have been discovered. But all of the previous ones were found indirectly, mostly from the wobble their gravity causes in their parent stars.

The two teams used different techniques. Berkeley’s Kalas relied on Hubble’s Advanced Camera for Surveys to tease out the Jupiter-size planet Fomalhaut b. The planet’s existence had been suspected since 2005, when Kalas studied a picture of a dust ring around the star.

He noticed the inner edge of the ring was sharply defined, raising his suspicion that there was something hiding in there that had a lot of gravity. Planets tend to sweep their orbits clean, either by ejecting pretenders or smashing them to dust.

As Kalas studied the image, made with the assistance of a coronagraph that blotted out the star’s light, he found a big chunk of something in the dust belt. A picture taken in 2006 showed it was indeed orbiting the star, located in the constellation Piscis Austrinus.

“The gravity of Fomalhaut b is the key reason that the vast dust belt surrounding Fomalhaut is cleanly sculpted into a ring and offset from the star,” Kalas said. “We predicted this in 2005, and now we have the direct proof.”

The planet would not be capable of supporting life as we know it. At 11 billion miles from its star, about three times as far from its sun as Pluto is from ours, it would be too frigid.

The huge amount of material in the dust ring, equivalent to three Earths, made the discovery possible by reflecting so much starlight.

The star is 16 times as bright as our sun. One reason it’s so bright is that it is relatively young, only 200 million years old. Our sun is 4.5 billion years old. But because Fomalhaut is burning so furiously, it will burn itself out long before our sun enters its dotage, in about 5 billion years.

The planet represents the lowest-mass planet yet found outside our solar system, Chiang said, bringing the day closer when researchers might be able to find Earth-like planets.

The second team, which included researchers from Lawrence Livermore National Laboratory in Northern California and the NRC Herzberg Institute of Astrophysics in Canada, took its photographs in infrared light.

“We’ve been trying to image planets for eight years with no luck, and now we have pictures of three planets at once,” said Bruce MacIntosh, an astrophysicist at Lawrence Livermore and one of the lead authors of the research paper.

Two breakthroughs made the discovery possible. First was the use of adaptive optics — a set of optical techniques that correct for the interference of the Earth’s atmosphere, which bends and twists incoming light. In recent years, adaptive optics has become so sophisticated that ground telescopes can make pictures every bit as crisp and eye-­popping as the Hubble Space Telescope. Because the mirrors of Gemini and Keck are so large, 26 and 32 feet across, respectively, they can gather even more light.

Scientists estimated that the three planets are roughly from seven to 10 times the size of Jupiter. Like Fomalhaut b, they are far from their parent star, ranging from 24 to 67 astronomical units. An astronomical unit is the distance of the Earth from the sun, about 93 million miles.

But it wasn’t their distance from HR8799 that enabled the researchers to spot them. It was their youth. The central star is only about 100 million years old, making the planets even younger, about 65 million years old. That means they are still glowing with heat from their formation, generating enough heat that they can be seen in infrared, even 130 light-years away.