Discovery of a Solar System More like Our Own for the First Time, Scientists Find Three Planets Orbiting a Distant

Article excerpt

For the first time, scientists have found more than one planet orbiting a star other than our own sun.

The discovery of three massive planets revolving around Upsilon Andromedae, a sun-like star 44 light years from Earth, will have a profound impact on how astronomers view the heavens.

Indeed, the fact that these three planets - each as large or larger than Jupiter - are all relatively close to the star they orbit is forcing scientists to come up with new models for how planets are created. But perhaps more intriguing, their mere existence implies that many other stars have more than one orbiting planet. And although these three planets are unlikely to harbor life, the discovery supports the theory that another Earth-like planet with conditions conducive to life may exist. "What makes it a milestone is that this is the first time we have found a planetary system around a star," says Alan Boss, an astrophysicist at the Carnegie Institution in Washington. "That's important because it helps buttress the belief that most of the objects that have been found so far really are planets as opposed to something else." Moreover, the findings, announced yesterday, are further evidence that planet-finding has become one of the most dynamic fields in astronomy. Considered a fringe science not long ago, researchers have now found 17 planets outside our solar system since 1995 with the help of new telescopes and better technology. The latest discovery, made by two teams of scientists, came out of a survey of 107 stars in the Milky Way galaxy - and years of minute observations. Using a technique called radial velocity measurements, astronomers watched for a telltale wobble in a star's orbit caused by the gravitational tug of an orbiting body. It was exactly such a wobble in Upsilon Andromedae's orbit that caught the attention of San Francisco State University astronomers Geoff Marcy, Paul Butler, and Debra Fischer. They located the closest planet orbiting Upsilon Andromedae in 1996 as part of a handful of major planet discoveries. But their calculations indicated that something else was acting on the bright star, which is sometimes visible from Earth. Further calculations pointed to the existence of a second and third planet, a finding that was independently confirmed by another group of scientists who had also been studying the star. To be sure, the discovery is a long way from extraterrestrial life. But it is a steady step along the way to proving that the heavens are dotted with planets. "It suggests that planet formation happens often, happens rapidly, and probably happens around every star like our sun," says Dr. Fischer. "This represents a profound shift in our model of how planets form." A freak science? Even a decade ago a finding such as Upsilon Andromedae's planets would have been unlikely, if not impossible. The concept of radial velocity was theoretical and had never been put to practice. Also, few scientists wanted to risk their careers on what was considered a freak science. …


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