Star Wars Planets: More Science Fact than Fiction


By Knicole Colon, PhD

The Star Wars universe is enormous, with hundreds of planets and moons that have a range of properties.  Given that astronomers have now discovered some ~1500 exoplanets along with, of course, the 8 planets and ~150 moons in our Solar System, it should be no surprise that astronomers are discovering more and more real planets that are similar to the fictional planets in the Star Wars universe.


First, let us look at Tatooine, the home planet of Anakin and Luke Skywalker.  The most unique feature of this planet is that it orbits around two stars.  In fact, one of the most iconic shots from the Star Wars movies is of Luke on Tatooine with two stars setting in the sky in the background.  Yet, up until a few years ago, astronomers were not sure if planets could actually exist in stable orbits around more than one star.  The Kepler mission changed everything when it discovered a planet orbiting two ordinary stars.  That planet, Kepler-16b, is most likely a gas giant planet that is more similar to Saturn than the rocky/desert planet that Tatooine is, but it is still exciting that planets with multiple stars like Tatooine do exist after all.  Plus, we now understand that there is no reason a planet can’t exist in a stable orbit, even in the habitable zone, around two or more stars.


Compared to Tatooine, Kamino is a bit less fantastical.  Kamino is an ocean planet where the clone army was created.  While I can’t speak to whether any clone armies exist somewhere in the real universe, it is a fact that water worlds like Kamino can exist.  GJ 1214b is an exoplanet that is a bit larger than Earth, and for awhile it was believed to be a pure ocean planet based on observations that probed its atmosphere.  It is now believed to have a uniform cloud layer high up in its atmosphere, but it is still possible that underneath that cloud layer, there exists one big ocean.  Maybe it’s even constantly raining there, just like in scenes on Kamino in Episode II!  Even though ocean planets really can exist, I don’t know that anyone would actually want to live on a water world where it’s potentially always raining.


If Kamino were further from its star and therefore a lot colder, it might be something like Hoth.  Hoth is (in)famous for being a frigid planet, covered by ice and snow.  During the so-called “polar vortex” this past winter, I recall hearing numerous references of Earth being very much like Hoth.  Since winter did eventually end here and summer is coming (unlike in Game of Thrones), Earth is not a good example of a real Hoth-like planet.  However, there is a growing number of small, potentially rocky exoplanets that orbit at very large distances from their host stars.  Being so far from the main source of heat in a planetary system means that these planets are quite cold, and could very well have Hoth-like climates.  One example is OGLE-2006-BLG-109Lc, which takes about 15 years to orbit its host star.  Based on the temperature of its host star and its orbital distance from its star, that planet has an estimated temperature of -360 degrees Fahrenheit.  I’m thinking that might be a bit too cold for anyone to survive there, so if anyone wanted to visit a “real” Hoth one day, we might need to find a planet that is a bit warmer.  Or, just wait until next winter comes.


On the opposite end, a lava planet like Mustafar is not an ideal place to settle down either.  Mustafar is the setting for the epic showdown between Darth Vader, (spoiler alert!) previously known as Anakin Skywalker, and Obi-Wan Kenobi.  In that fight scene, they have to take great care to avoid lava spewing at them.  Interestingly, the volcanic activity on Mustafar is supposed to be a result of the gravitational effect caused by two nearby gas giant planets.  This is very similar to the effect Jupiter has on its moons, in particular Io.  Because of gravitational stresses, Io is the most geologically active object in our Solar System, and images have even been taken of volcanic eruptions on its surface.  There are also known exoplanets that are so hot they probably have lava oceans, thanks to orbiting extremely close to their host stars.  One example is CoRoT-7b, which has an orbital period of just ~ 0.85 days or ~ 20 hours!  This was another discovery not expected by astronomers, simply because it was not believed that a planet could survive being so close to its host star.  While CoRoT-7b will likely be “eaten” by its star eventually, for now it is in a stable orbit, with lava likely flowing happily all over its surface.  For all we know, there is some villainous person like Darth Vader hiding there now, preparing to take over the universe.  We can only hope there is some Jedi-type person who is willing to brave the lava and take the villain down!


Last but not certainly not least, we have the Death Star.  Its name is quite misleading, since the Death Star is no star.  And, as Obi-Wan Kenobi also pointed out, “That’s no moon. It’s a space station.”  While the Death Star is a feat of engineering rather than an astronomical object, there was a bit of a ruckus in the astronomical community when pictures of Saturn’s moon Mimas were taken by the Cassini probe in 2005.  That’s because Mimas has a remarkably large crater on its surface, giving it a similar appearance as the Death Star.  Thankfully, the resemblance ends there.  Mimas does not have a powerful superlaser that is capable of destroying an entire planet.  But, if it did have a laser, and if it was used by villains to destroy the Earth, I imagine Earth’s  crumbled remains would eventually form what resembles an asteroid belt.  That is something to keep in mind – for any extrasolar asteroid belts that are discovered, we should consider that they could be the result of destruction by a Death Star.


As time goes on and astronomers keep hunting for planets, the fictional Star Wars planets are going to become increasingly realistic.  Still, we will never be able to find the “real” Tatooine or Hoth because those planets existed “a long time ago in a galaxy far, far away….”