The aliens, who call themselves Cytherians, are far more advanced than even the 24th century crew of the Enterprise. But they never left their home, preferring instead to send out deep space probes and reconfigure the spacecraft of other creatures to travel the breadth of the Milky Way to visit them.

A beguiling idea, that ancient and advanced civilizations might inhabit the core of the galaxy, but as new research shows, the problem is it is a highly implausible one. Life near the center of our galaxy never had a chance.

According to astronomer Antony Stark, of the Harvard-Smithsonian Center for Astrophysics, every 20 million years, on average, interstellar gas collects at the galactic center and compresses in an incredibly violent way, resulting in the rapid, chaotic creation of millions of new stars.

The phenomenon, as Stark and colleagues report in the Oct. 10 issue of The Astrophysical Journal Letters, results in a bumper stellar crop - in particular of super-giant stars, which are so massive that they cannot sustain their nuclear furnaces and soon blow themselves up in supernovae.

They explode so violently and so often that they blast everything within hundreds of light-years with lethal amounts of energy and radiation - enough to preclude the possibility of anything organic surviving.

The H-S team made their discovery using the Antarctic Sub-millimeter Telescope and Remote Observatory, or AST/RO, the world's only astronomical facility capable of compiling large-scale maps of the sky at sub-millimeter wavelengths.

The telescope is about 70 inches (1.7 meters) in diameter and it operates in one of the most severe environments on the planet - Antarctica's frigid desert. AST/RO is located at the National Science Foundation's Amundsen-Scott Station at the South Pole.

The air there is so dry and cold that radiation otherwise absorbed by water vapor in the Earth's atmosphere still can reach the ground and be detected by the instrument.

Stark and his team observed that the gas for each starburst comes from a ring of material located about 500 light-years from the galaxy's center. Gas collects there under the influence of a structure called the galactic bar.

It is a stretched oval of stars about 6,000 light-years long, which rotates in the middle of the Milky Way. Tidal forces and interactions with this agglomeration of stars cause the ring of gas to build up to higher and higher densities until it reaches a critical tipping point.

Then, the gas collapses inward, toward the galactic center and smashes together, fueling what astronomers call a starburst.

A starburst is star formation gone wild, Stark said.

Usually, when astronomers observe starbursts, they see them in galaxies in the process of colliding. But the process works in the center of individual galaxies as well, and it seems to happen with frightful regularity at the center of the Milky Way.

Powered by gravity and fueled by uncountable numbers of free molecules of hydrogen and other gases, the event is among nature's most spectacular. But it also is among the most lethal.

How soon will the next starburst hit the Milky Way's center? Relatively soon, Stark said. It likely will happen within the next 10 million years.

The assessment is based on measurements showing the gas density in the ring is nearing the tipping point. Once that threshold is crossed, the ring will collapse and a starburst will blaze forth on an unimaginably huge scale.

About 30 million solar masses' worth of matter will gather, so much that it will overwhelm the supermassive black hole at the galactic center - which astronomers estimate is about 3 million times the mass of the sun.

The black hole will be unable to consume most of the gas - Stark likens it to trying to fill a dog dish with a firehose. Instead, the leftover gas will form millions of new stars.

Any danger to Earth and its future inhabitants? Unlikely. Even if thousands of the new stars go supernova, the explosions would be too far away - more than 25,000 light-years - to affect either the planet or its local stellar neighborhood.

A bit closer in, however - say, within 1,000 light-years - and anything living would be annihilated. No Cytherians there. The writers of Star Trek got it wrong that time.

The center of the galaxy is not a placid place where civilizations can flourish. Rather, it is a super-energetic zone where stars - if not life - are created by the bushel.

The really peaceful area of the Milky Way is right where Earth is now. Finding other possible living planets means searching the other outskirts of the galaxy's massive, spiral arms.

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