Kepler 1647b, a planet newly seen and identified by astronomers using NASA’s Kepler Space Telescope, is the largest planet to orbit two suns.
Planets that orbit two suns are called circumbinary planets, and finding them "is much harder than finding planets around single stars,” San Diego State University astronomer William Welsh said,
according to a release promoted by NASA. “The transits are not regularly spaced in time and they can vary in duration and even depth.”
A transit is when a planet passes in front of a star, and astronomers look for slight dips in brightness to indicate it has occurred, NASA explained. Advanced computer programs are utilized to confirm circumbinary planets, which are also known as Tatooine planets, named after Luke Skywalker's home planet in "Star Wars."
Kepler-1647 is 3,700 light-years away toward the constellation Cygnus and about the same age as Earth at 4.4 billion years old. The planet's two suns are similar to our sun, with one slightly larger and the other slightly smaller.
The newly discovered planet is described as a gas giant about the size of Jupiter,
Space.com reported. It orbits its suns in 1,107 Earth days and is within a "habitable zone," in which liquid water could be stable.
While the gas giant doesn't have a solid surface, it's possible that a moon circling it could support life, Space.com said.
Astronomers first noticed Kepler-1647's transit in 2011,
The Washington Post reported. But the planet's long orbit made confirming it more difficult than the smaller circumbinary planets that have previously been confirmed.
"With one transit it's hard or impossible to tell what's going on," Veselin Kostov, a NASA Goddard postdoctoral fellow said. "So we had to wait for three years for the planet to transit again, during which time we kept a close eye in the system, analyzing the available data and gathering new observations."
The discovery was announced at an American Astronomical Society meeting in San Diego on Monday. Welsh is the co-author of research recently accepted for publication in the Astrophysical Journal.