Astronomers using telescopes not much larger than the spyglass Galileo wielded 400 years ago have discovered a new Jupiter-sized planet orbiting a bright, distant star.

It is the first planet to be discovered by an international network of astronomers using telescopes no larger than those sold at Wal-Mart for the same price as an iPod.

“This portends a new era in planet hunting,” said Geoff Marcy of the University of California-Berkeley, whose team has discovered nearly 60 new planets, but was not involved in this survey.

It was only a decade ago that the world’s most sophisticated telescopes with mirrors more than 30 feet across were beginning to notice celestial hints – a star’s wiggle here, a brief dimming there – that planets orbit stars far beyond our solar system.

Now telescopes with optics just 4 inches wide costing a few hundred dollars are scanning the heavens for signs of these new worlds. Of course, precise navigation systems, powerful computer software and several Ph.D.s working full-time are part of the formula for success, too.

Still, the discovery suggests it won’t be long before the hunt is joined by backyard astronomers armed with off-the-shelf equipment, loads of time and enough caffeine to stay awake. Just last winter a Kentucky man in his backyard found a new nebula, or star nursery, that had been overlooked by scientists at major observatories.

“You might think that you need a big telescope to do this, but that’s not really true,” said Guillermo Torres of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

Torres is one of 12 astronomers from six institutions that collaborated to find the new planet. Details are online in Astrophysical Journal Letters.

“The follow-up work requires very specialized techniques, so this is something that most people couldn’t buy in a shop and do right away,” Torres said. “But the hardware is fairly simple.”

Other planet hunters say the small telescopes’ success is “quite significant” because it makes the search cheaper and simpler, which could accelerate the pace of planet discoveries.

“But you still need automated telescopes to really cut down the operating costs,” said University of Texas astronomer William Cochran, who recently spotted a new planet using the Hobby-Eberly Observatory in west Texas, which combines 91 hexagonal mirrors to form a light-gathering surface 30 feet across.

Planet-hunting beyond our solar system is perhaps the most glamorous race in astronomy, with at least 123 identified.

In a separate announcement Wednesday, European astronomers said they had discovered yet another new planet using more conventional techniques. Their new planet is interesting, they said, because its dimensions are more Earth-like. It is the second planet to be found orbiting a star in the constellation Altar 50 light-years from Earth.

But it is the new “little telescope that could” method that has researchers buzzing.

The new planet in the constellation Lyra 500 light-years from Earth was the first to be spotted by the Trans-Atlantic Exoplanet Survey. (An exoplanet is one that orbits a star other than the sun.)

Small telescopes assembled with off-the-shelf parts were set up at Palomar Mountain in California, the Lowell Observatory in Arizona and Astrophysical Institute of the Canary Islands near Africa. The instruments examined 12,000 bright stars over a three-year period.

The telescopes looked for a brief dimming in a star’s brightness, indicating a planet might have moved across the star’s face. This method previously has been used to confirm planet sightings, but this is the first time it has been used to detect a new planet using such modest instruments, researchers said.

The sophisticated technique has been compared to standing in Boston and spotting the shadow of a mosquito flying in front of a searchlight in New York City.

“All that we have to work with is the light that comes from the star,” said study co-author Timothy Brown of the National Center for Atmospheric Research in Boulder, Colo. “It’s much harder to learn anything when the stars are faint.

“The fact that we can learn anything at all from a planet that is 500 light-years away is astonishing,” Brown said in a statement.

Astronomers confirmed the discovery by using the giant Keck I telescope in Hawaii, following the established method of planet detection that measures how a planet’s gravitational tug makes a star wobble ever so slightly.

The new planet, known as TrES-1 (pronounced Trace One) is a hot, Jupiter-sized gas giant orbiting just 4 million miles from a star in Lyra. By comparison, Earth is positioned 93 million miles from the sun. It zips around its star in 72 hours, meaning a year on the planet equals just three days on Earth.

“This planet is nothing like our own solar system,” Torres said. “It’s really close to the parent star. Why hasn’t it evaporated? There are a lot of questions forming about this planet.”

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On the Web:

Harvard-Smithsonian Center for Astrophysics: http://cfa-www.harvard.edu/previous/latest.html

AP-ES-08-25-04 1453EDT