Planet on Left Planet 'seen' around distant sun Scientists say they have photographed a planet outside the Solar System for the first time. The European Southern Observatory group said the red image is the first direct shot of a planet around another star. The planet, known as 2M1207B, is about five times the size of Jupiter and is orbiting at a distance nearly twice as far as Neptune is from our Sun. The parent star and planet are more than 200 light-years away near the southern constellation of Hydra. There has been a lot of competition among astronomers to secure the first direct picture of an exoplanet. When the ESO group first released the picture last September there was doubt over whether the star and planet were gravitationally bound. The new images essentially confirm our 2004 finding Benjamin Zuckerman, UCLA But follow-up images taken at the Very Large Telescope facility in Chile show the two objects are moving together. "Our new images are quite convincing," said Gael Chauvin, an Eso astronomer. "This really is a planet - the first planet that has ever been imaged outside of our Solar System," he added. Tough task It is extremely difficult for current technology to detect exoplanets - let alone getting a clear shot of one. All of the 130 or so exoplanets so far discovered have been found using indirect methods - looking for changes in the properties of stars (their brightness or way they move) that can be explained only by the presence of a planet. Now we have a direct observation, the European and American team says. The star has the uninspiring catalogue number 2M1207A. It is a brown dwarf, or "failed star" - an object whose mass of hydrogen and helium has failed to trigger the nuclear reactions that would make it shine brightly like normal stars. At the time of 2M1207B's discovery, it was impossible to prove that the red speck caught in the original images was not a background object, such as an unusual galaxy or a peculiar cool star. The new observations show with high confidence that the two objects are moving together and hence are gravitationally bound. "The two objects - the giant planet and the young brown dwarf - are moving together; we have observed them for a year, and the new images essentially confirm our 2004 finding," said Benjamin Zuckerman, a University of California-Los Angeles (UCLA) professor of physics and astronomy. Anne-Marie Lagrange, another member of the team from the Grenoble Observatory in France, looks towards the future: "Our discovery represents a first step towards one of the most important holy grails of modern astrophysics: to characterise the physical structure and chemical composition of giant and, eventually, terrestrial-like planets." Dr Chauvin added: "Given the rather unusual properties of the 2M1207 system, the giant planet most probably did not form like the planets in our Solar System." "Instead it must have formed the same way our Sun formed, by gravitational collapse of a cloud of gas and dust." As a consequence, there are bound to be some scientists who will still question if 2M1207B really is a planet. Lynne Hillenbrand, an assistant professor of astronomy at the California Institute of Technology, told the Associated Press news agency: "The claim of an object being a planet is subject to one's definition of planet, and there are different camps on what that definition is." What everybody wants is a direct image of a rocky planet like Earth circling another star. But this will not come until we get the next generation of super-telescopes capable of resolving such small, faint objects. The latest research has been accepted in Astronomy and Astrophysics, a premier journal in astronomy. http://news.bbc.co.uk/1/hi/sci/tech/4501323.stm wow!
Good stuff, Meowgi... Particularly interesting to me because I happen to be in the middle of reading 'Space' by James Michener. Thanx.
I always thought a planet was a satelite of the sun and a moon was a satelite of a planet. Unless you have 2 suns bound, which would be cool to see.
There's a big raging debate about what's considered a planet involving Pluto. Is it a planet or an Oort Cloud object (giant snowballs in a halo on the distant edge of the solar system)? My understanding is that a planet must be in a not ecessively elliptical orbit around a star, not undergoing thermonuclear reactions like a star and a meet a minimum size. So the moon doesn't qualify since its orbitting the Earth even though if it was orbiting the sun on its own would be big enough to be a planet, comets don't qualify since they have extremely elliptical orbits and are small, asteroids don't qualify since they are too small. The problem with Pluto is its small and also has a fairly elliptical orbit. As far as ball of gas most of the outer planets are balls of gases so I don't think composition matters.
Agree with Sishir's interesting post. I recently saw a talk by a planetary scientist, and basically, if you use technically precise definitions, you have two options: (1) Pluto included, with a total of about 11 "planets," since there are two objects discovered since Pluto that are at least as large and have similar orbits. (2) Pluto discounted as a planet, for a total of 8 "planets." Nobody is seriously considered changing the definitions, since we'd have to reprint about 4 billion elementary schools textbooks.
I think most people now believe that Pluto-Charon is a "binary planetesimal" or something like that. In other words rather than a clearly defined system of planet & satelite they are more like uncompleted pieces of planet formation that didn't quite make it. Pluto & Charon have less mass seperation than any planet-satelite in the solar system by a long way and so sort of rotate around each other. There are also many other binary systems like Pluto & Charon, and even larger bodies (Sedena or Quaoar?). Moons are very diverse in terms of formation. Phobos and Deimos around Mars are both probably captured asteroids. Luna (aka The Moon) is probably the ejecta from a large impact with Earth. The rings around the gas giants were moons going to be moons but were too close to overcome tidal forces. Several of the moons around Saturn and Jupiter are only temporary captures, and will within several million years be shot out of the solar system.
