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.

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.

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.

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.