Astronomers from around the globe have announced the detection of at least nine possible extrasolar objects, presumed to be gas-giant planets orbiting nearby stars. If confirmed, the finds could bring the total number of planets detected beyond our solar system to 50.

Included in the collection of newly discovered objects is the smallest extrasolar planet yet detected a gas giant roughly half the size of Saturn. In addition, astronomers have brought to light new evidence that several nearby stars may actually have multiple-planet systems. These and other extrasolar planet findings were discussed today at the International Astronomical Union assembly in Manchester, England.

"We're very encouraged for the next generation of planet-hunters."

Until recently, the number of known extrasolar planets (sometimes called exoplanets) had stalled at 41. And of these, only one sun-like star Upsilon Andromedae had been found with multiple planets surrounding it. This latest increase in number of detected planets, coupled with the fact that many now seem to have companion objects orbiting near them, bolsters astronomers hopes about the possibility of finding Earth-like planets orbiting other stars.

Since many extrasolar planets are too far away to see directly, astronomers must detect extrasolar planets by carefully watching stars to see if they "wobble," or slightly shift their center of mass. Just as the moon has gravitational effects on Earth, and each of the solar-system planets has a slight effect on our sun, any large object orbiting a star will tug at that star, causing the star to move slightly. When searching for extrasolar planets, astronomers see slight shifts in a stars light as an alert that some object perhaps a planet may be orbiting it.

Using ground-based telescopes from around the world, astronomers have now detected wobbles from a new batch of stars. Though their studies will have to be reviewed by other experts in the exoplanetary field, it is highly likely that these new wobbles mean the existence of never-before detected planets outside our solar system. Whats more, several of these stars now seem to show unexplained wobble behavior, a condition that many scientists think is evidence for second and even third planets orbiting them.

Some of the most recent extrasolar findings include:

• From the University of California, Berkeley: three new planets, five known/new planets that may have companion planets or stars
• From the Geneva Observatory: five additional new planets, one known planet that may have a companion planet or star
• From the University of Texas, Austin: one new planet

Scientists say these latest discoveries add a great deal to the existing literature on extrasolar planets, and even hint to the fact that extrasolar terrestrial (rocky or irony) planets may outnumber the gas giants that astronomers have so far discovered.

"Sadly, our detectability limit prevents us from seeing [lower-mass planets]," said Debra Fisher, a post-doctoral fellow at UC Berkeley. However, she added that astronomers research to date suggests low-mass planets may outnumber high-mass planets surrounding nearby stars.

For now, astronomers must rely on helpful but often limiting ground-based observatories to detect extrasolar planets. But NASA has ambitious plans to launch two new space-based telescopes dedicated to the pursuit of Earth-like planets beyond our solar system in the near future.

The Terrestrial Planet Finder project, scheduled for launch in 2013, will use specialized instruments to detect and photograph extrasolar planets, and even analyze planetary atmospheres. And in 2006, NASA will launch the Space Interferometry Mission (SIM), which will help astronomers better detect wobbly stars.

"Were very encouraged for the next generation of planet-hunters," said Fischer.