Scientists discover a giant Alien planet that orbits two suns – and could have habitable moons
Some worlds have more than one sun in their sky. Now scientists say they’ve confirmed the existence of the largest-ever planet orbiting a pair of binary stars – a gas giant with the same mass and radius as Jupiter. Exoplanets like this one – situated in their stars’ habitable zone and massive enough to lasso in many rocky moons – could be an interesting place to go looking for signs of alien life.
At about 2.7 astronomical units (AUs) from its suns (Earth is 1 AU from ours) Kepler-1647 b is in the habitable zone of its stars. That means it’s in the magic sweet spot that experiences the right amount of sunlight and heat to allow liquid water to form. But the planet itself wouldn’t actually be home to life as we know it: It’s almost entirely made of gas. If it’s anything like the gas giants in our solar system, however, it likely has dozens of moons – and just like the moons that orbit Saturn and Jupiter, those little rocky worlds could be great places to look for life like ours.
Scientists find exoplanets by measuring the way the light of their host stars dimwhen the planets “transit,” or pass in front of the stars from our perspective. This is way harder to do with circumbinary planets, or CBP.
“CBPs are harder to detect because their transits are not strictly periodic,”Veselin Kostov, a NASA Goddard postdoctoral fellow and lead author of asoon-to-be-published study on the planet, told The Washington Post in an email. “A planet around a single star is like a clock. For example, if you are outside the solar system and can see Earth in transit, you’ll see the transit every year. Every 365 days you’ll see a tiny decrease in the light from the Sun as Earth moves across its disk. In contrast, when a circumbinary planet transits, the consecutive events can be early or late by many days. Sometimes, the transits of a CBP can even cease altogether, only to reappear decades, even centuries later,” he said.
Scientists like to study systems with multiple host stars because they help us understand the myriad ways in which solar systems can evolve: It’s been just a few years since we confirmed that planets could form in these strange, star-heavy systems, and now we know that in addition to (relatively) small planets kept in close orbit, the systems can develop large, slightly further-flung planets.
“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,” study co-author William Welsh of San Diego State University said in a statement.