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Red Giant Sun May Not Destroy Earth Site Index Subscriptions Shop Newsletters HOME ANIMALS ENVIRONMENT HISTORY NEWS HOME ANIMAL NEWS ANCIENT WORLD ENVIRONMENT NEWS CULTURES NEWS SCIENCE & SPACE NEWS KIDS WEIRD NEWS MAPS NEWS Red Giant Sun May Not Destroy Earth PEOPLE & PLACES PHOTOGRAPHY Anne Minard for National Geographic News 15 Most Popular News Pages VIDEO September 14, 2007 WORLD MUSIC The first glimpse of a planet that survived its star's red giant phase is Photos in the News offering a glimmer of hope that Earth might make it past our sun's News Videos NATIONAL eventual expansion. GEOGRAPHIC MAGAZINE The newfound planet, dubbed V391 Pegasi b, is much larger than Earth but likely ADVERTISEMENT MAGAZINES orbited its star as closely as our planet orbits the sun (explore a virtual solar system). SHOP LATEST PHOTOS IN THE NEWS SUBSCRIPTIONS When the aging star mushroomed into a red Photo Gallery: Frozen Inca Mummy TV & FILM giant about a hundred times its previous size, Goes On Display V391 Pegasi b was pushed out to an orbit TRAVEL WITH US nearly twice as far away. OUR MISSION Solar Plane Sets Record, Makers Say "After this finding, we now know that planets with an orbital distance similar to the Earth can survive the red giant expansion of their parent Hubble Fans Dispute "Sharpest" Title Enlarge Photo stars," said lead author Roberto Silvotti of the National Institute of Astrophysics in Napoli, Italy. Printer Friendly • Catalog Quick "But this does not automatically mean that even More Photos in the News Shop Email to a Friend the Earth, much smaller and much more vulnerable [than V391 Pegasi b], will survive" our • Books & Atlases RELATED sun's expansion billions of years from now, he NATIONAL GEOGRAPHIC'S PHOTO OF THE DAY • Clothing & Future Universe Will "Stop said. Accessories Expanding," Experts Suggest (June • Today's Photo Silvotti and colleagues present their research in 4, 2007) • Download as Wallpaper • DVDs this week's issue of the journal Nature. Images: The Stormy Sun • Maps Opposing Forces Photos: Hubble's Top Ten NEWS FEEDS Discoveries At an age of ten billion years, V391 Pegasi b is Sign up for free Get our news delivered directly to your desktop—free. one of the oldest known planets. The planet and How to Use XML or RSS Newsletters its host star are in the constellation Pegasus, about 4,500 light­years from Earth. Once a month get new photos Podcasts The red giant star is six times hotter than our sun and its surface gravity is ten times and expert tips. National Geographic to Go greater. National Geographic News, Sign up Videos, and More But when it was a middle­aged star, "it had a mass similar to that of the sun, and Download Podcasts stably fused hydrogen into helium for billions of years," writes Jonathan Fortney in a ADVERTISEMENT review article also appearing in Nature. Fortney is a scientist at the NASA Ames Research Center in Moffett Field, California, FREE NEWSLETTER who was not involved in the new paper. Sign up for our free Inside National Geographic Stars like the sun become red giants when the hydrogen in their cores burns fully into newsletter. helium. At that point they expand, becoming large enough to engulf any inner planets. Every two weeks we'll send you our top stories and photos (see sample). Continued on Next Page >> Site Index Subscriptions Shop Newsletters HOME ANIMALS ENVIRONMENT HISTORY NEWS HOME ANIMAL NEWS ANCIENT WORLD ENVIRONMENT NEWS CULTURES NEWS SCIENCE & SPACE NEWS KIDS WEIRD NEWS MAPS NEWS Red Giant Sun May Not Destroy Earth PEOPLE & PLACES PHOTOGRAPHY << Back to Page 1 Page 2 of 2 15 Most Popular News Pages VIDEO Most experts think that the sun will enter its red giant phase in about five WORLD MUSIC billion years. Photos in the News Researchers have long argued whether Earth and the other inner planets in our solar News Videos NATIONAL system will be destroyed at this point or just get pushed out to more distant orbits. GEOGRAPHIC MAGAZINE (Related: "Solar System's Fate Predicted by ADVERTISEMENT MAGAZINES Nearby White Dwarf?" [December 21, 2006].) SHOP LATEST PHOTOS IN THE NEWS In a 2001 study in the journal Icarus, Kacper SUBSCRIPTIONS Photo Gallery: Frozen Inca Mummy Rybicki of the Polish Academy of Sciences in TV & FILM Goes On Display Warsaw and co­authors proposed one scenario. TRAVEL WITH US OUR MISSION Mercury and Venus would evaporate, the team Solar Plane Sets Record, Makers Say said, while Mars would remain intact and be Enlarge Photo pushed away. Printer Friendly The sun will actually expand and contract Hubble Fans Dispute "Sharpest" Title Email to a Friend several times during its red giant phase. If those expansions are brief enough, Earth just might RELATED survive. • Catalog Quick More Photos in the News Shop Future Universe Will "Stop Scientists know two main forces will affect the Expanding," Experts Suggest (June • Books & Atlases outcome, but neither is well understood. 4, 2007) NATIONAL GEOGRAPHIC'S PHOTO OF THE DAY • Clothing & Images: The Stormy Sun One is the mass loss of the sun, which happens Accessories during the bloating phase. This expansion tends • Today's Photo Photos: Hubble's Top Ten • DVDs to push planets out, and since the star is less • Download as Wallpaper Discoveries massive, its gravity is weaker and the planet can • Maps settle into a more distant orbit. NEWS FEEDS The other force is a tidal friction, which draws Sign up for free planets into the star. Get our news delivered directly to your desktop—free. How to Use XML or RSS Newsletters "For the Earth, the delicate balance between these two processes leads to a rather Once a month uncertain fate," said Frederic A. Rasio, a professor of physics and astronomy at get new photos Northwestern University, who was not involved in the study. Podcasts and expert tips. National Geographic to Go National Geographic News, Sign up Silvotti, author of the new study, echoed that uncertainty, adding that finding V391 Videos, and More Pegasi b is a good first step to understanding what might happen. Download Podcasts ADVERTISEMENT But whatever happens to Earth in the future, Silvotti holds no hope that wildlife will be around to witness the sun's changes. FREE NEWSLETTER "And concerning [the fate of] human life in particular," he said, "I am afraid we have much more urgent problems than this." Sign up for our free Inside National Geographic newsletter. Free Email News Updates Every two weeks we'll send you our top stories and Sign up for our Inside National Geographic newsletter. Every two weeks we'll send photos (see sample). you our top stories and pictures (see sample). .
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