Professor Geoffrey Marcy of San Francisco State University announced the discovery of a planet orbiting 70 Virginis (in the constellation Virgo) and one orbiting 47 Ursa Majoris (in the Big Dipper). These planets are believed to be the only possible explanations of characteristic "wobbles" that have been observed in measurements of the gravitational variations of their host stars.
Marcy believes that the planet orbiting 70 Virginis is about nine times larger than Jupiter and orbits its host in 116 days. The heat from 70 Virginis would keep the planet at about 185 degrees Fahrenheit which would allow for the presence of liquid water. This could possibly permit the formation of amino acids and proteins, the complex organic molecules that are believed to have led to life on Earth. Although Marcy believes that this planet may not have a solid surface, he said that it may have moons where life could form.
Another planet found orbiting 47 Ursa Majoris is believed to have a mass of about 3 times the mass of Jupiter with a circular orbit of about 3 years. Although it may also have water, it would probably be frozen, says Marcy, comparing it to the polar regions of Mars.
Robert A. Brown of the Space Telescope Science Institute says of this planet, "It is the first find with characteristics of mass and orbit that are similar to the solar system," he said. "We know of only one way to get such a thing and that is to have an event around that star that is the same event that happened around the sun. And that event produced an Earth, the one planet that does support life. This is the first evidence that what occurred around the sun (formation of a family of planets) has occurred around at least one other star," said Brown.
Marcy and many other astronomers believe that these are just the first of many planets to be found. "All of us will find more, I'm sure of it," says Marcy. "We already have hints in our data." He and his team are monitoring 120 other stars and are currently analyzing the data from 60 of them.
Alan Boss of the Carnegie Institute of Washington agrees. "We are truly in the dawn of a new era," said Boss of the. "We'll probably be finding more new planets in coming years."
"What has been left to the imagination is now going to be the subject of scientific inquiry and there is going to be an answer," says Brown. Marcy believes that a new opportunity has opened up for astronomers. "We are at a watershed," he says. "There is a dawning of a new field in science. These new planets offer a challenge to us to compare them with those in our solar system."
-Compiled by Kirsten Tynan