Evrim Yazgin
Cosmos science journalist
Happy Star Wars Day! On this “May the 4th Be With You,” Cosmos is celebrating the epic space opera created by George Lucas by compiling a list of real exosolar planets, or exoplanets (planets outside our solar system), which may resemble some of the fictional worlds in Star Wars.
Strap yourselves in as we engage our hyperdrive and travel to a galaxy far, far away…
(Well, actually, all these exoplanets are within our own Milky Way – but there’s still a striking similarity!)
Tatooine – Kepler-16b
Binary sunsets
The home world of Anakin and Luke Skywalker – the Jedi father and son duo whose lives and conflicts form the main thread of the Star Wars films – is the desert planet Tatooine.
Apart from being hot and dry (and having a surprising tendency to produce ultra-powerful beings who hold the fate of the galaxy in their hands), Tatooine is known for its twin suns. One of the most magical moments in the entire Star Wars franchise is the scene in the first film, Star Wars: A New Hope (1977), in which Luke wistfully watches the binary stars set over the sandy horizon as he contemplates his future. John Williams’ score here is particularly moving.
Binary star systems, in which two stars orbit tightly around each other, are surprisingly common in our galaxy – accounting for up to 85% of the star systems in the Milky Way. While it is rare, there have been about a dozen circumbinary planets (planets that orbit twin stars) found.
We can’t say for sure if a planet with Tusken raiders and podracing exists, but one exoplanet in at least, Kepler-16b, is a massive Saturn-mass planet with a binary sunset like Tatooine. While it is not a desert planet (it is a gas giant), it shows that planets can be found orbiting binary stars. Kepler-16b is 245 lightyears from Earth and was first discovered 10 years ago by NASA’s Kepler satellite.
Bespin – many (TOI-197)
Gas giant
As gas giant, Bespin was home to a “city in the clouds” in the second Star Wars film, The Empire Strikes Back (1980). According to Wookieepedia, Bespin was about 118,000 km in diameter, making it just a smidge larger than Saturn.
While we don’t have to look beyond our own solar system to find planets that resemble this Star Wars world, there are many exoplanets that also fit the bill.
NASA confirmed last year that, after 30 years of exoplanet discoveries, we passed the 5,000-planet mark. Roughly 30% are gas giants around the size of Saturn or Jupiter, or even bigger.
In 2019, a “hot Saturn” was found using NASA’s Transiting Exoplanet Survey Satellite. Called TOI-197, the planet orbits very close to its host star. This makes it much warmer than Saturn, which has a chilly average temperature of between -140°C and -180°C.
Mustafar – 55 Cancri e
Lava world
The scene of Anakin and Obi-Wan Kenobi’s epic duel at the end of the 2005 Star Wars: Revenge of the Sith, Mustafar is an inhospitable volcanic lava world.
At 41 lightyears away, we don’t currently know if 55 Cancri e is a volcanic world, but one thing is for sure: it is hot. The planet is so close to its star that its surface temperature is roughly 2,400°C. It’s also tidally locked to the star, like the Moon is to Earth, so only one side of the planet always faces its star. That side is probably always covered in lava.
But this planet isn’t exactly the Chosen One. The major difference between 55 Cancri e and Mustafa is that 55 Cancri e is probably too hot for an awesome lightsabre duel between old friends-turned-foes. Anakin and Obi-Wan would disintegrate if they touched down on its surface. This exoplanet’s power is not to be underestimated.
Kamino – TOI-1452 b
Ocean world
Kamino is the ocean-covered world on which the Kominoans created the clone army appearing in Star Wars: The Clone Wars (2002).
Scientists last year discovered an exoplanet, TOI-1452 b, which they believe could be covered in a deep ocean. The planet orbits binary stars in the Draco constellation about 100 light-years from Earth. It sits in the “Goldilocks zone” where it is neither too hot, nor too cold for liquid water to exist on the planet’s surface.
But an estimate of the radius, mass and density of TOI-1452 b suggests that water could make up 30% of the planet’s mass.