Moment of Wonder: Spinning Around Two Suns

An artist's impression of a stellar eclipse and planetary transit events on Kepler-1647. Credit: Lynette Cook

NASA has announced its discovery of the largest known planet that orbits two suns. These bodies are known as circumbinary planets, or “Tatooine planets,” after Luke Skywalker’s home world.

The planet Kepler-1647b — roughly the mass and radius of Jupiter — is 3,700 light-years away and an estimated 4.4 billion years old, about the same age as Earth. The stars it orbits are similar to our own sun, with one slightly larger and the other a little smaller.

A team led by astronomers from Goddard Space Flight Center in Greenbelt, Maryland, and San Diego State University (SDSU) in California identified the planet using NASA’s Kepler Space Telescope. The discovery was announced this week in San Diego at a meeting of the American Astronomical Society.

“(Finding) circumbinary planets is much harder than finding planets around single stars,” said SDSU astronomer William Welsh, one of the coauthors of the NASA study on the planet. “The transits are not regularly spaced in time and they can vary in duration and even depth.”