Does 'Planet 51' Really Exist?

The new animated film"Planet 51" (TriStar) boldly takes astronaut Capt. Chuck Baker whereno one has gone before: to a life-harboring planet outside our solar system.There he finds a quaint 1950s society of little green people who are afraid ofanything (or any one) that is different.

"In1950s America, the drive-in was king and screen heroes fought invaders fromouter space," said director Jorge Blanco. "But it was also a time ofincredible social paranoia ? people actually believed that their neighbor couldbe an undercover agent trying to take over their minds."

"Shreck"screenwriter Joe Stillman unfolds the plot from there with thinly veiled spoofsof communist sympathizers, McCarthy-esque finger pointing, scientific ignoranceand social change that will be lost on younger viewers but amusing to grownups.

Chuck(voiced by Dwayne Johnson) lands his spaceship next door to a backyard barbequein the "nice and peaceful" town of Glipforg, setting off a "Warof the Worlds" panic that brings the military in from its top secretextraterrestrial tracking station known as "Base 9." Lem, the teenagejunior assistant planetarium curator, and the one reasonable citizen on Planet51, befriends Chuck and risks social ostracism and criminal charges to help thestranger from another planet.

Meanwhile,local hippies march in protest to the military action: "We're upset! Wereally are!"

Indeed,the world view on Planet 51 ? to say nothing of its cosmology ? is safe,predictable and narrow. The universe is 500 miles long and contains more than1,000 stars. The only known intelligent life exists right there on Planet 51,where the comic-book store is "the greatest source of scientificknowledge."

Inaddition to clever messages about social tolerance, "Planet 51" givesus another chance to ponder the possibility of life on planets outside oursolar system, as astronomers have done for nearly two centuries. As of lastmonth, 405 so-called "exoplanets" orbiting far-away stars have beendiscovered in increasingly rapid fashion as new techniques allow scientists tozero in on and characterize the heavenly bodies. Thirty new exoplanets werediscovered in October alone.

Thered-dwarf star Gliese581, located 20 light years from Earth, has at least four planets. One,called Gliese 581 d, is considered a "super-Earth"with a mass some 8 times that of our planet. To support life, scientists say aplanet must orbit its star within a distance not too cold to freeze liquidwater and not too hot to boil it. With a 66-day orbit around its medium-hotstar, Gliese 581 d is squarely in the "just-right" zone.

Thispast August, Earthlings sent more than 25,000 messages to Gliese 581 dby radio telescope. Although close to Earth by astronomy standards, the planetis plenty far away; senders estimate the missives will arrive in time for thewinter holidays in 2029.

Butwill Glieseans be advanced enough to respond?

Calculations by researchers at the University of Edinburgh suggestthere could be at least 361 intelligent life forms in the Milky Way alone ? andpossibly as many as 38,000 if you count life spreading from one planet toanother during asteroid collisions. They looked at the combination of stars andplanets needed to form a solar system that can support life, and the likelihoodof life surviving long enough to develop into biologically complex andintelligent creatures able to communicate across the stars.

"Even if alien life forms do exist, we may not necessarily be ableto make contact with them, and we have no idea what form they would take,"said Duncan Forgan, a graduate student who carried out the research. "Lifeon other planets may be as varied as life on Earth and we cannot predict whatintelligent life on other planets would look like or how they mightbehave."

Fortunately, on Planet 51 anyway, everyone learned how to get along.

This article was provided to inpartnership with the National Science Foundation.

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