Show spotlights galaxy's 'billions of planets'

Worlds without end populate our universe, with NASA estimating that 6 billion planets the size of Jupiter orbit stars in our Milky Way galaxy alone. There may be many billions of smaller orbs.

So far in the past dozen years since the technology became available, astronomers have discovered 212 planets around nearby stars, says California & Carnegie Planet Search. One of these exoplanets is believed to circulate in the Cinderella zone around a star — where it's not too cold and not too hot. It has been dubbed a "super Earth" because of its size.

Although good direct photos of these planets are not yet possible and instruments aren't precise enough so far to detect worlds as little as Earth, scientists have gleaned a great deal of information about exoplanets and their environments. Some stars are known to have multiple-planet systems, and many of the planets discovered so far are gas giants closely orbiting their stars.

Water vapor has been detected in the atmospheres of exoplanets. Differences in temperature in one far-off sphere were mapped indirectly, allowing scientists to clock strong winds in the atmosphere.

But nobody has had a good look at an exoplanet. Fortunately for Utahns, scientists have made many solid deductions.

The best information available on exoplanets has been assembled to provide a preview of what some of these strange worlds may be like. The digital astronomical program, "Extreme Planets," which took more than a year to produce at Clark Planetarium, is now showing there.

Starting at 7 p.m. Tuesday, the script's author — Ray Villard, news director of the Space Telescope Institute — is scheduled to lecture about the subject. His talk will be followed by a showing of "Extreme Planets," with tickets available at two for $15. For more information on the talk, check out the planetarium's Web site, clarkplanetarium.org.

"We were able to take a lot of discoveries over the last couple of years about extra-solar planets," said Mike Murray, production manager for the project. "We know how close they are to their suns, what kind of suns they are. ... We can actually simulate what it's like on these planets, what they look like close up."

Some of these are as close as 10 light-years away, some 10 times that distance, he said. While most are in the range of three to four times the size of our solar system's largest planet, Jupiter, "we hope that there are some that are the size of Earth," he said.

Technology may soon allow researchers to detect the relative small-fry planets that are of greatest interest to the denizens of this relatively minute world.