– It has to be one of the most iconic scenes in film history. Luke Skywalker, burdened with a purpose yet unknown to him, stares with uncertainty at a beautiful alien sunset. It's a masterpiece of modern filmmaking, but I'm here to say that it would even better in real life. Here's why. (electronic music) Let's take a moment to look at this scene again. Ooh, that's some good sci-fi. This scene is unmistakable, but what I want to show you is that it can be made even better with science. Specifically, living on a planet orbiting two suns has some surprises in store for its inhabitants. Unless you're an astronomer, I think it's natural to assume that our solar system set up is the universal norm, like this perfectly drawn and circular chart shows, but that's not the case. In the last few decades, we've learned that most stars that you can see in the night sky are in fact multiple star systems where planets could be orbiting two or even three or more stars.
Oh, poor Neptune. Oh, poor Neptune, I forgot you. Oh, I'm so sorry. Don't worry, no one noticed. Of course, Tatooine is a planet orbiting two stars. Given the fact that both of Tatooine's suns are visible in the night sky and they're about the same size, we can assume that Tatooine is a circumbinary planet, or a planet that is orbiting two stars which themselves are orbiting the stars' combined center of mass. Here's where science makes this scene even better. Even though we don't know how fast Tatooine rotates as a planet and binary stars can orbit each other every day or every thousands of years, there is one consequence of the cosmos that we don't see in Star Wars: A stellar eclipse. If Tatooine is a circumbinary planet, then according to the physics alone, it should have sunsets like this, and the next night it can have a sunset like this.
Awesome! Or rather, look at this. (humming Star Wars music) Pretty cool right? This is just the beginning of how cool the Tatooinian sunset you're looking for could be. I know we all assume that Tatooine has suns the same size of our star and that Tatooine is tilted in the same way that the Earth is, but the universe is a big place with a lot variations on what's possible. It's just as possible that Tattoine's two suns orbit each other like the Earth and the Moon does, or the Earth and the Sun, with one star much much larger than the other dictating how they move around each other. Then a Tatooinian sunset might look like this to Luke. Again, depending on planet tilts and orbital periods, with stars of different sizes eclipsing each other multiple times during their orbit, and the beauty of this is it even visualizes some of the theme's of Star Wars. David and Goliath, rebel vs empire. But binary stars can also orbit each other's barycenter or combined center of mass for orbiting bodies in an ellipse. Ooh, look at all these big words we're using.
(laughs) Now imagine seeing this while surveying a moisture farm's landscape and thinking about your life. So much cooler. Because we never see a full day on Tatooine, the sunset really could be in any one of these configurations. We have proof! We have proof. In 2011, the Kepler space telescope discovered a binary star system named Kepler-16. (light saber) NASA knew it was a binary system and that it had a planet orbiting around it like Tatooine might because of how the sunlight dipped from Earth's perspective. In other words, NASA discovered a Tatooine like planet looking at the very thing that makes a Tatooine so special: the eclipses. If you lived on a planet in the star system like Kepler-16b, which NASA also discovered, you would see eclipses, two of them involving two suns every 41 days. No two sunsets would look alike for weeks. This isn't even happening in a galaxy far far away, this is happening in our own Milky Way just 200 light years that way. (humming Star Wars music) We've known about binary star systems for hundreds of years, but George Lucas, credit where credit is due, was the first person to really popularize just how beautiful a sunset in a binary star system would be, and now, 40 years later, we actually have enough evidence to say it would look even cooler, even more science fictiony than Star Wars predicted, and I think that's beautiful in its own way, Because Science.
Thank you so much for watching. Make sure to follow me on Twitter, where you can suggest ideas for future episodes, and on Instagram under the same name where I'm now posting behind the scenes videos and extra rants and stuff. And a special announcement, more because science gear in the Nerdist store. Go to Nerdist, click on the store, and you can find mugs, and T shirts, and pins, all with a phrase that's fun and sciency to say and makes sense in a lot of contexts and is also this YouTube show. So head over there, sport your nerdery. I'm sure in the movies they have this worked out, but depending on the orbits of the stars that Tatooine is orbiting around, and how quickly Tatooine spins, the day night cycle on Tatooine might just be straight up trash where you have no sunlight, or all sunlight, or like two hours of night. You would.
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