A trove of newly discovered planets orbiting other stars suggests that the solar system may not be the oddball it had begun to seem. Among eight newly identified extrasolar planets, three have large, circular orbits that resemble those of the planets in the solar system. One of the planets is at least 80 percent as massive as Jupiter and orbits the star HD 4208. If it were part of the solar system, it would be about as far from the sun as Mars is. Two other planets, each with a minimum mass 2.8 times that of Jupiter, circle the star HD 23079.
The new finds, announced Oct. 15, bring the tally of extrasolar planets to nearly 80. In August, when the count was at 70, only two of the planets had orbits large enough and circular enough to resemble the paths of planets in the solar system (SN: 8/18/01, p. 100). All the rest either circle their parent star so closely that they graze its outer atmosphere or they have large, highly elongated paths that bring them alternately very close and very far from their parent star.
Planets that lie at greater distances from their parent require a longer time--years rather than months--to be detected.
Most of the planetary systems that researchers initially found bear little resemblance to the solar system, says study collaborator Steven S. Vogt of the University of California, Santa Cruz. After years of observations, "we're starting to see something like …