In Galileo's Footsteps.(International Edition; ASTRONOMY)(European Southern Observatory's telescope)

For the first time in hundreds of years, the most powerful telescopes may soon come from Europe.

Galileo has been getting a lot of press lately, and no wonder. Four centuries ago this year, the Italian genius pointed his small, primitive telescope at the night sky and saw wonders nobody had imagined. His discoveries transformed our view of the heavens, but also infected astronomers with a permanent desire to peer just a bit deeper in the universe and find a few more cosmic secrets. Which is why, less than 20 years after they put the finishing touches on a generation of telescopes so big they would have made the Renaissance stargazer swoon, the astronomers are at it again. Three teams are racing to build telescopes four times wider and with up to 16 times the light gathering power than what exists now, and to have them trained on the stars by 2018.

For the first time in literally hundreds of years, the most powerful entry in this race comes not from the United States but from Europe. Armed with big plans and a relatively stable source of funding, the 13-nation European Southern Observatory is on track to have the hottest astronomical hardware on the planet--along with the chance to find the coolest stuff in the universe.

The American teams are hardly conceding defeat, of course. Like rival football coaches, the leaders of each effort are already touting their advantages, albeit in a polite and intellectual sort of way. "There's room for different designs," says Jerry Nelson of Caltech, who is designing the Thirty Meter Telescope, or TMT. Though it's smaller than the Europeans', he says, "I'm confident that ours is the most efficient." The Giant Magellan Telescope (GMT), spearheaded by the Carnegie Observatories, in Pasadena, California, is the smallest of the three, but, says Carnegie director Wendy Freedman, "We're convinced we'll have the best imaging."

In a telescope, size matters--especially the mirror, which gathers the starlight and focuses it into a meaningful image. The Keck telescope mirror atop Hawaii's Mauna Kea volcano spans 10 meters and is made of small glass segments fitted together; the largest ...