Scientists Discover Gas Planet Deep Within Our Galaxy

Scientists have discovered a gas planet located deep within our galaxy - about 13,000 light-years away - making it one of the most distant planets known, according to new research.

"We don't know if planets are more common in our galaxy's central bulge or the disk of the galaxy, which is why these observations are so important," lead author Jennifer Yee of the Harvard-Smithsonian Center for Astrophysics (CfA) said in a statement.

This latest discovery is credited NASA's Spitzer Space Telescope, which teamed up with the ground-based OGLE's Warsaw Telescope at the Las Campanas Observatory in Chile. Using a technique called microlensing, the telescope scans the skies for far-away planets. This is when one star happens to pass in front of another, and its gravity acts as a lens to magnify and brighten the more distant star's light. If that foreground star happens to be orbited by a planet, the planet might cause a blip in the magnification.

Thanks to this microlensing method, scientists have found about 30 planets so far, with the farthest sitting about 25,000 light-years away.

"Microlensing experiments are already detecting planets from the solar neighborhood to almost the center of the Milky Way," said co-author Andrew Gould of The Ohio State University, Columbus. "And so they can, in principle, tell us the relative efficiency of planet formation across this huge expanse of our galaxy."

However, the downfall is that microlensing can't always give the precise distance to the stars and planets being observed. Thus, of the approximately 30 planets discovered with microlensing so far, roughly half cannot be pinned down to a precise location.

That's where Spitzer comes in. When combined with a ground-based telescope it can see the star brighten at a different time due to the large distance between the two telescopes and their unique vantage points - referred to as parallax.

So scientists used the time delay between OGLE's and Spitzer's viewing of the planetary event to calculate the distance to the newfound planet and its passing star.

It turns out that this unnamed planet is located about 13,000 light-years away in the farthest reaches of our Milky Way galaxy, and is about half the mass of Jupiter.

Spitzer will watch approximately 120 additional microlensing events this summer, and scientists hope that there are many more planets just waiting to be discovered.

"We've mainly explored our own solar neighborhood so far," concluded Sebastiano Calchi Novati, a Visiting Sagan Fellow at NASA's Exoplanet Science Institute at the California Institute of Technology. "Now we can use these single lenses to do statistics on planets as a whole and learn about their distribution in the galaxy."

The findings were published in The Astrophysical Journal.

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