It looks like there may be more bright-eyed, sandy-haired moisture farmers out there than we thought. In a new study, astrophysicists Scott Kenyon and Benjamin Bromley suggest that rocky planets like Tatooine can in fact orbit two stars. And we’re ready to dance off into the twin-sunset at the thought of it.
This isn’t the first time scientists have discussed the the reality of planets existing in Lucas-approved orbits – we actually know that these binary systems exist. Since its launch in 2009, NASA’s Kepler space telescope has spotted seven planets orbiting binary stars, including the infamous first find: Kepler 16-b, “Where your shadow always has company.” But the problem is that like Saturn or Jupiter, these planets are all thought to be inhabitable gas giants. “None of those found by Kepler so far are small and rocky like our Earth – or Tatooine – for that matter,” says Bromley.
He adds that this may be because small planets are harder for instruments like Kepler to measure, but astrophysicist and science writer Dr Matthew Francis explains it may be more than that. Orbiting two suns successfully is not easy. Like the animals in our world, objects in space prefer to take a simple path. Adding more stars to a system makes orbit more complicated, and inherently less stable, he explains.
The problem is that the small bits that form rocky planets, called planetesimals, need to merge gently together in order to grow. When planetesimals orbit a pair of stars, “their paths get mixed up by the to-and-fro pull,” says Bromley. “Their orbits can get so tangled that they cross each other’s paths at high speeds, dooming them to destruction, not growth.” We essentially end up with a mass of Endor-worthy stormtrooper-tree collisions happening simultaneously. Not good in any situation.
But using mathematical simulations inspired by Pluto and its large moon Charon, which many astronomers view as a binary planet system, the team found that solid celestial bodies should in fact survive if they take what’s known as the “most circular orbit” (which looks like an oval-shaped orbit with ripples). “We took our sweet numerical time to show that the ride around a pair of stars can be just as smooth as around one,” the team writes. “[We’re suggesting] that the same recipe that works around the sun will work around Tatooine’s host stars if the stage is set right.”
Time to start building our sandworm bunkers? Not quite.
“Of course, there are a lot of factors at play here,” notes Lights In the Dark space blogger Jason P. Major. “For example, the type of stars involved. If one of the stars happens to be a red dwarf (M-type) it remains to be seen if it could host life on a rocky planet. M-dwarfs are long-lived, but tend to be highly active with flares, etc. Combine one with another star – and that’s a lot of radiation to fend off.”