In fact, before this decade, astronomers had been frustrated in their attempts to find any extrasolar planets at all. Astronomers said yesterday's announcement should kill lingering suspicions that these bodies are not really planets, but dim, failed stars known as brown dwarfs. This is a major discovery. This will shake up the theory of planet formation. In 1996, Marcy and colleague R. Paul Butler, of the Anglo-Australian Observatory, had detected the innermost planet around Upsilon Andromedae, one of many lone planets they have found in surveys of hundreds of sunlike stars from the Lick Observatory in California and the powerful Keck telescope in Hawaii.
Technology is incapable of imaging conventional planets directly.
Planet hunters use an indirect technique that measures a wobble induced in a star by the gravitational tugs of circling planets. More massive planets, and those orbiting most closely to stars, produce the strongest, most quickly readable signals. But in the case of Upsilon Andromedae, the researchers noticed suspicious scatter patterns layered over the first wobble signature. By February, as they had hoped, they had accumulated enough observations to confirm the presence of a second planet there. The third planet popped right out of the screen.