Word: planet
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Dates: during 1990-1999
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...were wrong. As it happened, Butler was in the middle of rewriting the software last October to accommodate the spectrometer's newly heightened sensitivity when a disconcerting flood of E-mail started pouring in. Michel Mayor and Didier Queloz, of the Geneva Observatory in Switzerland, had just detected a planet circling the star 51 Pegasi, lying 45 light-years away in the constellation Pegasus. Says Queloz: "We first thought that our instrument was faulty, but repeated verifications and computations finally convinced us that we had bagged a planet...
...astronomical discovery has disappeared on a closer look, though, so Marcy and Butler headed for the telescope, determined either to debunk or verify the Swiss team's claims. Sure enough, says Marcy, after four nights at Lick and many hours of computer time, "everything they'd said about the planet was confirmed." (Butler and Marcy did, however, show that hints the Swiss team had found a second planet around the same star were mistaken...
...object turned out to be peculiar. It's half as massive as Jupiter, but orbiting closer to 51 Pegasi than Mercury is to the sun. That means its surface temperature is 1300ūC, hotter than a blast furnace. Still, it is a planet. "I was a little schizophrenic about it," says Marcy. "On the one hand, we had been scooped. But I also felt euphoric that humanity had entered a new era in which new worlds were going to be subject to exploration...
...also a beginning of sorts. Faced with the existence of these planets, astronomers must now revise their theories to fit the new facts. To begin with, theorists have to scramble to explain how the 51 Pegasi planet could have formed and survived intact so close to its parent star. The planet around 70 Virginis is also problematic: its orbit is egg-shaped rather than circular, which suggests to some astronomers that it formed more like a star than like a planet. Indeed, many experts think it is technically a brown dwarf--a star that never got big enough to ignite...
What the data may be saying is simply that the dividing line between stars and planets may be less distinct than astronomers had believed. "Everything found so far poses challenging questions for planetary formation theory," says astronomer Robert Stefanik, of the Harvard-Smithsonian Center for Astrophysics. That was underscored last week when, after weeks of government shutdown, results were released from a NASA experiment much closer to home. The probe's plunge from the Galileo spacecraft into Jupiter's atmosphere showed that the planet has higher winds, less lightning, less water, helium and neon, and--at the point of impact...