NASA researchers have announced the discovery of the largest known planet to orbit twin suns. The announcement was made at at a meeting of the American Astronomical Society, and the team’s findings will be published in an upcoming issue of the Astrophysical Journal.
The planet, Kepler 1647-b, is around 3,700 light-years away and close to 4.4 billion years old, making it roughly the same age as Earth. The planet orbits two stars, one of which is slightly larger than our sun while the other is slightly smaller. Even though Kepler 1647-b is an uninhabitable gas giant, the planet’s moons might be suitable for life.
The discovery was made using NASA’s high-powered Kepler Space Telescope, which looks for regularly repeating lapses or dips in starlight called transits. These transits occur when an orbiting planet passes in front of a star, momentarily blocking out its light in relation to the telescope orbiting Earth.
These types of planets are sometimes colloquially referred to as “Tatooine” planets after Luke Skywalker’s twin-sun-orbiting homeworld of the Star Wars franchise. Discovering circumbinary planets - planets that orbit twin stars - is more difficult than finding planets that orbit a single star like Earth. Because the planets orbit two separate stars, the transits that telescopes observe can be irregular or have long, complex repeating patterns that are difficult to analyze.
Kepler 1647-b takes 1,107 days to orbit its twin stars, giving it the longest known orbit of any circumbinary planet, and its mass is roughly equivalent to Jupiter’s. According to William Welsh, co-author of this study, the find is important because it confirms long-standing hypotheses about the diversity of solar systems in the universe:
Habitability aside, Kepler-1647 b is important because it is the tip of the iceberg of a theoretically predicted population of large, long-period circumbinary planets
Kepler 1647-b was discovered over five years ago, but it took years of computer-aided calculations to determine it was indeed a circumbinary planet. Amateur astronomers in the crowdsourced KELT Follow-Up Network aided in the calculations of the planet’s orbit and mass.
Findings like this one show that no matter how much we think we know about the cosmos and our position in it, new discoveries will always reveal that ours is indeed a mysterious universe.