NASA's Spitzer Space Telescope and OGLE's Warsaw Telescope, a ground-based telescope located at the Las Campanas Observatory in Chile, have teamed up to discover a gas planet located approximately 13,000 light years away. Given its distance from Earth, the planet is now one of the most remote planets ever discovered.

The discovery was made through a method known as microlensing. A microlensing event happens when a star passes in front of another. The star's gravity serves as a lens that magnifies and brightens the light of the more distant light of a star.

If the foreground star is being orbited by a planet, the planet could cause a blip in magnification. Using these blips, astronomers have so far been able to discover about 30 planets, with the farthest located about 25,000 light years away.

Andrew Gould from The Ohio State University, Columbus said that microlensing experiments already detect planets from the solar system's neighbor to almost the Milky Way's center.

"They can, in principle, tell us the relative efficiency of planet formation across this huge expanse of our galaxy," Gould said.

OGLE's Warsaw Telescope scans the sky for microlensing events, but since the technique can only detect the presence of planets and cannot determine their location, Spitzer provided the lacking information, giving scientists more information on where the planet is located. Such technique involving two telescopes studying an object from different vantage points is called parallax.

Jennifer Yee from the Harvard-Smithsonian Center for Astrophysics (CfA), one of the authors of three studies published in the Astrophysical Journal, which described the collaboration between scientists using the OGLE and Spitzer telescopes, said that traditional parallax techniques using telescopes based on Earth are not very effective when great distances are involved.

Spitzer, which currently circles the sun and is located about 128 million miles away from Earth, is in fact, the first space telescope that used microlens measurements for a planet.

For the newly discovered planet, the microlensing event occurred about 150 days. Both the space and the ground telescopes found a planetary blip, albeit Spitzer saw it occur 20 days earlier. The time delay between the viewing of the two telescopes was then used for calculating the distance between the star and its planet, allowing scientists to determine the planet's mass, which is approximately half of Jupiter's mass.