MORE NEW WORLDS
AWAIT DISCOVERY

philip e daoust

FOLLOWING A YEAR of discovering new planets, San Francisco State University researchers Geoffrey Marcy and Paul Butler say they won't be announcing additional findings any time soon.

"I don't have time for any research any more," Marcy said. "So, no new planets will be found by Paul Butler or me for many months, perhaps years." Marcy said they spend most of their time now responding to media requests--as many as 20 per day.

Butler said he will continue to analyze data collected over the summer but that it may be a year or more before any new findings are announced. He's confident, however, that more planets will be discovered.

"Over the next five years maybe we will find another 50 to 100 planets," he said.

Endless Number

Astronomers now believe that there may be an endless number of planets in the universe, many that will never be found and others that could challenge conventional theories of how planets are formed and how the universe itself came to be.

"The galaxy has a 100 billion or there-about stars, so you can expect there would be many hundreds of millions of planets. We are obviously in the very early stages of scoping them out."

Furthermore, Butler said no less than five percent of all stars have large, Jupiter-size planets orbiting them. "I would guess that most stars have planets," he said, adding that many of those could be Earth-size or smaller.

Last year the team confirmed the first-ever planet found outside our solar system. The initial discovery of a planet orbiting the star 51 Pegasi was made by a pair of Swiss scientists. But they were unsure if the large object orbiting 51 Pegasi, a star about 55-60 light years from earth, was a brown dwarf (a huge star mass) or a large planet.

Only with a fine-tuned technique, sophisticated computer programs and close analysis were Butler and Marcy able to determine that it was indeed the first planet to have been discovered outside our planetary system.

They used a technique called "wobble velocity" to do their analysis. Wobble velocity is similar to Doppler Shift. Wobble does not guarantee the presence of an orbiting planet--many stars wobble. But it's the first variable examined when making a determination. The final determination is made through complex analysis of data collected from a star's wobble--rate, extent, frequency of wobble, etc.

The finding launched the California scientists into the world spotlight, but it was only the beginning of their extra-solar planet treasure hunt. Over the ensuing months, they independently discovered five new planets.

Latest Discovery Raises Age-Old Question

Last month Marcy and two astronomers from the University of Texas confirmed they had found an eighth extra-solar planet some 85 light years from Earth.

The newest planet, found orbiting the star 16 Cygni B, apparently has an eccentric orbit. Its orbit is elliptical, unlike any other orbit known to exist in the Milky Way galaxy.

Scientist are also excited about the giant planet's distance from its star--far away enough to be neither too hot nor too cold--raising the possibility that it could contain liquid water, the essential ingredient for life on Earth.

The possibility of life existing on other planets is not far reaching, Butler said, especially if water is present.

But it will be years, if not decades, before scientists can get a better idea of the composition of these distant planets. Butler said two or three of the planets they have discovered are so positioned that water could exist in liquid form.

The string of extra-solar planet findings has given renewed legitimacy to the search for life elsewhere in the universe.

In August, NASA stunned the world when it announced that a meteorite found in the Antarctica, and believed to have come from Mars, possibly contains a fossil micro organism. If the finding is true, it could lead to scientists discovering life on Mars and give credibility to calls for further probes into outer space.

However, Butler, like many scientists, is skeptical of the Mars discovery.

"I don't necessary believe that they actually found remnants of life in those rocks," he said, "but I don't discount it either." Butler said more information is needed to make any theories about life existing on Mars, but he did say there is "no question" the red planet once contained running water.

"The possible Mars discovery of life really doesn't affect our detection of planets," Marcy said. "But, if Mars did once harbor life, then it is extremely likely that planets outside our solar system would also develop the biochemistry of replicating molecules and leading to Darwinian evolution."

Yet the planet finders have nothing to do with the search for life in outer space, Butler said. "We are not searching for any kind of life. Heck, we wouldn't even know how you go about doing it."

NASA Renews Own Search

Marcy and Butler's findings, combined with the Mars rock discovery, have spurred NASA researchers to renew proposals to expand their own search for extra-solar planets.

John McDonald, a researcher at the SETI Institute based at NASA's Ames Research Center in Mountain View, Calif., said he and fellow astronomers want to search for smaller planets outside our solar system--planets which are more Earth-size than the larger ones Marcy and Butler have been finding. Those discovered by Marcy and Butler are Jupiter-size and larger.

"Marcy and Butler's work is parallel to ours, and doesn't actually change our mission plans. Their work, however, strongly supports the likelihood that if there are large planets, like the ones they have discovered, there are probably small Earth-like planets as well," said McDonald.

Unlike Marcy and Butler's technique, the NASA scientists will measure "brightness variations" of many stars, McDonald said. They will look for a "dip" in the light emitted from a star as a planet passes in front of it.

"By observing many stars simultaneously, we should detect a wide variety of planets, some of which will be in the so-called 'habitable zone' around each star, where liquid water, thick atmospheres and possibly life will exist."

World's Largest Telescope

Butler and Marcy have collected an enormous amount of data from their continued observations at the Lick Observatory east of San Jose and the Keck telescope on the 14,000 foot summit of the Mauna Kea volcano in Hawaii. The Keck is the world's largest telescope.

Astronomers from around the world dream of getting a chance to look at the universe through the Keck's super-powerful lens. NASA has reserved time for the two researchers on the telescope this year and next.

"A few years ago NASA kicked in 30 to 40 million for time on the Keck and now have about 90 to 100 nights reserved for the next year," Butler said.

Using the Keck telescope, the planet-finding team is able to collect data from approximately four hundred stars, compared to about one hundred at the Lick. The data collected will continue to be analyzed by Butler, Marcy and a few graduate students working with them on their cosmic search.

"This telescope permits us to observe 400 Sun-like stars," Marcy said, "and enables detection of Saturn-like planets, in addition to the Jupiter-like planets that we have already found."

Observatory in Space

Within the first decade of the next century, NASA has said it plans to launch a huge platform deep into outer space that would contain powerful telescopes capable of blocking out the light glare from certain stars, allowing astronomers to focus in on the planets orbiting them.

Butler is enthusiastic about the project because of the possibility of looking at the planets he and Marcy have discovered. "The prospects are exciting," he said. "Taking a spectrum of the planet allows you to figure out its composition."

While the scientists know that the newly found planets are indeed planets--and not something else, like huge star masses--they have never actually seen them. The planets are too far from Earth for current telescopes to detect.

"All we actually see," said Butler, "is the velocity wobble that the planet imposes on the parent star, so we don't know what these planets are made of. What we know is the orbit of the planets, and that we know quite precisely."