Weird World

By MICHAEL D. LEMONICK

Astronomers have long been convinced that the universe must be filled with planets orbiting faraway suns. In the past couple of years, scientists have even detected such planets indirectly, by measuring the wobbles their gravity imposes on their host stars. But no one expected actually to photograph any of these distant worlds until well into the next century, when the next generation of superpowerful telescopes goes into space. Yet that's precisely what the Hubble telescope seems to have done. NASA announced last week that the space telescope has snapped what scientists believe is the first picture of a planet outside our solar system.

It's a giant: a big, gaseous sphere more than twice as massive as Jupiter and some 450 light-years from Earth. Susan Terebey, an astronomer at the Extrasolar Research Corp. in Pasadena, Calif., discovered it quite by accident while studying a cloud of gas in the constellation Taurus where a lot of stars are being born. When Terebey and her colleagues looked closely at one double-star system, they noticed a long wisp of gas trailing off into space, and at the end of the wisp, a tiny dot of light.

If the dot is a planet, as astronomers strongly suspect, its gaseous state and high gravity would make it an extremely inhospitable place. It also seems to be hurtling away into space at thousands of miles an hour, flung outward by the twin stars' combined gravity. That's the only reason it's visible at all: conventional planets are too close to their stars to be seen in the glare.

Nevertheless, the discovery reinforces the notion that the galaxy is full of other worlds, some of them almost certainly Earthlike--and at least a few of which must harbor life.

--By Michael D. Lemonick