Courtesy of Business Insider
Artist’s rendering of the planetary system of HR 8799 at an early stage in its evolution, showing the planet HR 8799c, as well as a disk of gas and dust, and interior planets.
Astronomers could one day create rough maps of the continents and oceans on far-away planets, determining the balance of oceans, lands, and overhanging clouds.
The technique uses reflected starlight off the surface of an exoplanet. To test the idea, researchers analyzed data from the Deep Impact spacecraft, which has observed Earth from far away, to distinguish between natural surfaces on our own planet.
"The analysis told us there were three important features," study researcher Nicolas Cowan, of Northwestern University, told Inside Science News Service, "and their spectra look an awful lot like land, ocean, and clouds."
Cowan presented the technique in January at a meeting of the American Astronomical Society in Long Beach, Calif. He uses the colors of light that get reflected off the surface of a planet to determine how much land and ocean there might be on its surface.
It's like determining what someone is watching on TV by looking at the colors reflected off of the opposite wall in a dark room.
For this technique to be used on actual exoplanets, researchers will need to develop a telescope that's strong enough to see these pinpricks of light reflected by a distant world, which won't be possible for at least another decade.
That's not the only way we can get a handle on what other planets are made of, though. Researchers were just able to determine the atmospheric makeup of a relatively close planet.
The study, published in the journal Science on Thursday, March 14, used direct imaging of the solar system HR 8799, which lies about 130 light-years from Earth. Four planets around the star are visible to astronomers.
The star system is young, probably only 30 million years old, and these planets are extra huge gas giants, so not any planet that would be habitable for humans, but it's a start. It's possible this planetary system could hold smaller, more Earth-like planets as well, though they are too small to see.
The researchers zoomed in one of the outer planets, called HR 8799c, they could see water vapor and carbon monoxide in its atmosphere.
"The most exciting part of this result is that we were able to make these observations of an exoplanet atmosphere with this level of detail, much more than I even imagined was possible," study researcher Quinn Konopacky, of the University of Toronto, said in a press conference. "We have broken the light from the planet down to such a fine level of detail that the chemical fingerprints of the molecules in the atmosphere are breathtakingly sharp and distinct. This is important because it requires data of this quality to truly probe the makeup of a planetary atmosphere, and in turn, say something about how the planet formed."
Getting a good view of these exoplanets could help us understand which are the best to investigate as possibly habitable — the next Earth. So far, we've found more than 800 exoplanets, though none seem to be "just right" enough to move to yet.
One of the discovery images of the planetary system obtained by the Keck II telescope using the adaptive optics system
and NIRC2 Near-Infrared Imager.