The Atmospheres of Alien Worlds: Exoplanets Revealed by NASA

Alien worlds may seem like something out of science fiction, but they're everywhere. Today, there are more than 800 confirmed exoplanets, which are planets that orbit stars beyond our solar system. Now, researchers are learning a bit more about the atmospheres of these planets, which may help them find one that's capable of supporting life.

In order to actually examine these exoplanets, astronomers used ground-based telescopes that take infrared pictures of the planets posing near their stars. Yet these pictures are even more valuable when they're broken down into a rainbow of different wavelengths. Now, scientists are beginning to install infrared cameras on ground-based telescopes equipped with spectrographs, which could help revolutionize the way they view these exoplanets.

Spectographs are instruments that spread an object's light apart. This helps reveal signatures of molecules. So far, researchers have installed a spectrograph at the Palomar Observatory near San Diego. There, they examined HR 8799, a large star orbited by at least four known giant, red planets.

"In just one hour, we were able to get precise composition information about four planets around one overwhelmingly bright star," said Gautam Vasisht of JPL, co-author of the new study detailing the findings, in a news release. "The star is a hundred thousand times as bright as the planets, so we've developed ways to remove that starlight and isolate the extremely faint light of the planets."

After examining these planets, the researchers found that all four planets were nearly the same temperature. Despite this, though, the planets had very different compositions. Some, unexpectedly, did not have methane in them. Instead, they discovered that there may be hints of ammonia or other compounds on the planets. In order to better understand the chemistry of these four planets, though, the astronomers will have to employ further theoretical modeling.

Yet while they study these four planets, their hunt continues to obtain more and better spectra of exoplanets. Researchers plan to use ground-based telescopes to find more planets that are ripe for giving up their chemical secrets. Ideally, the astronomers want to find young planets that still have enough heat left over from their formation. This, in turn, will give the spectrographs more infrared light to see. In addition, the researchers want to find planets that are located far from their own stars and out of the blinding starlight.

"We're looking for super-Jupiter planets located far away from their star," said Vasisht in a news release. "As our technique develops, we hope to be able to acquire molecular compositions of smaller, and slightly older, gas planets."

The findings are published in The Astrophysical Journal.

Want to learn more about these exoplanet-finding techniques? Check out the video below, courtesy of the Jet Propulsion Laboratory and NASA.