The potential for life on other planets has been upped thanks for a recent new discovery. Until now, the binary systems discovered—that is, those with two stars—had only one planet, at least among those that NASA telescopes have seen. But in the past week the government’s star gazers have found not one but three planets orbiting a binary star system, and one of them may be in what scientists call the habitable zone—one that could contain liquid water and therefore, conceivably support life.
The surprise isn’t that there are two suns; it’s that more than one planet managed to form amid the complex gravitational fields generated by the configuration, NASA scientists say.
"Not all stars are single,” NASA says in the video below. “Astronomers estimate that more than half of the stars in the galaxy have companions. There are double, triple and even quadruple star systems."
NASA’s Kepler Mission telescope has been scanning the skies for decades searching out planets. It finds them by noting subtle drops in light emanating from a star when the planet passes in front during the course of its orbit, much the way the Transit of Venus caused a virtually unnoticeable drop in sunlight back in June.
In this way NASA has discovered 77 planets over the years with direct observation. And by inference, NASA theorizes that Mother Earth could have more than a hundred billion sisters, in the Milky Way alone.
"Astronomers detected two planets in the Kepler-47 system, a pair of orbiting stars that eclipse each other every 7.5 days from our vantage point on Earth," NASA said in a statement. "One star is similar to the sun in size, but only 84 percent as bright. The second star is diminutive, measuring only one-third the size of the sun and less than 1 percent as bright."
The discovery last fall of one planet orbiting a two-star system was exciting enough, resembling as it does the planet Tatooine, the supposedly science fiction world that Luke Skywalker grows up on in Star Wars. But the discovery of two planets throws most of what scientists thought they knew about planet formation out the window.
"The presence of a full-fledged circumbinary planetary system orbiting Kepler-47 is an amazing discovery," said Greg Laughlin, professor of Astrophysics and Planetary Science at the University of California in Santa Cruz, in a NASA statement. "These planets are very difficult to form using the currently accepted paradigm, and I believe that theorists, myself included, will be going back to the drawing board to try to improve our understanding of how planets are assembled."
Beyond that, the discovery brings even closer the tantalizing possibility of life existing on other planets, said William Borucki, Kepler mission principal investigator at NASA's Ames Research Center in Moffett Field, California, in the statement. "In our search for habitable planets, we have found more opportunities for life to exist."
Space.com's infographic diagrams this type of star system well, and below, NASA’s video explains the phenomenon and its significance.