Wednesday, August 12, 2015

Circumbinary Planets

Much of the new Star Wars trailer happens on Tatooine (And I'd love to know who crashed that Star Destroyer).

Until very recently, Tatooine was considered impossible. It's what we call a circumbinary planet - a planet that orbits around two suns. For this to happen, the two suns have to be close together. (If they're further apart, any planets will be non-circumbinary or S-type planets, orbiting only one of the two suns).

We've now discovered a number of circumbinary planets, and the latest, Kepler-453 b, is in the habitable zone (of the 10 circumbinary planets discovered, 3 are in the zone). However, this isn't Tatooine - Kepler-453 b is believed to be a gas giant (It could theoretically have habitable moons, however - and think about that. Living on a moon around a gas giant and having two suns to deal with).

The planet also has a tilted orbit. If we hadn't spotted it now, it would have been 50 years before we could have detected another transit.

As a note, planets have also been found in three and four star systems. We still don't understand how planets can even form in complex solar systems.

Cixin Liu explores the idea of a planet in an unstable multiple system in The Three-Body Problem (probably the best science fiction novel I've read recently - and I just realized it has sequels. Get them translated stat!)