60 Million Years Young
About 130 light-years from Earth, HR 8799 is visible in autumn from the Northern Hemisphere with binoculars shortly after sunset, Marois said.
Unlike our solar system, which is believed to have formed about 4.6 billion years ago, HR 8799 and the planets around it are probably about 60 million years old, Marois said.
The three planets are giant—probably around seven times the mass of Jupiter, Marois said.
"The next step is to do spectroscopy"—the study of the light wavelengths emanating from the planets—"to be able to study their composition and the details of the atmosphere," Marois said.
The second big exoplanet discovery this week is Fomalhaut b, the first exoplanet to be captured in a visible-light photograph, according to study leader Paul Kalas of the University of California, Berkeley. The work isbased on pictures taken by the Hubble Space Telescope.
Fomalhaut b is no more than three times the mass of Jupiter, Kalas said.
The planet takes 872 years to orbit its star, Fomalhaut, one of our closest neighbors at 25-light years from Earth. Sky-watchers in the Northern Hemisphere can see this bright star in the summer as part of the constellation Piscus Austrinus (Southern Fish), the astronomer said.
Astronomers have suspected a planet orbits Fomalhaut since 2005, when Hubble sent back pictures of a ring or dust belt around the star.
Signs of a planet's gravitational pull were visible in the dust belt's sharply defined inner edge and in the ring's off-center arrangement. (See the telltale 2005 image.)
"We're really excited, because not only do we have a planet, we can see how it interacts with this vast belt of comets and asteroids," Kalas said.
Marc Kuchner, a NASA researcher who specializes exoplanets, said the photographs of Fomalhaut b could herald a new era of planet detection.
"There are many other rings around stars like Fomalhaut that are probably pointing the way to planets," said Kuchner, who was not involved with the studies published today.
"It suggests that there's going to be a whole series of discoveries like this."
The Next Earth?
The exoplanets reported today are gaseous, like Jupiter. The next step will be to find rocky planets like Earth—planets that could potentially harbor life as we know it.
Kuchner said such detection will require instruments that are one thousand to ten thousand times stronger than those in use today—which is no reason to be discouraged, he said.
"When there are exciting discoveries like the ones [announced today], you never know what that will do to make things go faster, to inspire people to come up with new ideas and find new resources," Kuchner said.
Still, most scientists expect the discovery of another Earth will take some time.
"I think everybody is dreaming the dream of taking a picture of a terrestrial planet orbiting a star," the Herzberg Institute's Marois said. "But I think that's going to take a while."
SOURCES AND RELATED WEB SITES