Did Rey Skywalker ride a monster 260 foot wave on Kef Bir, the Ocean Moon of Endor?

Rey looks pass giant waves to see the ruins of the Death Star on Kef Bir in Rise of Skywalker

When I first saw the giant waves in the latest Star Wars movie, Rise of Skywalker, it took my breath away. Massive, huge and slow-moving, they were the perfect menacing grey-green monsters to create a barrier to the ruins of the second Death Star and the location of a Sith Wayfinder. But the Falcon crashed, so how was Rey to cross the giant surf? With a skimmer of course. And within minutes, we see a woman raised on a desert planet skillfully riding a skimmer through massive swells, deftly navigating the giant waves. Real or fantasy? How big were those waves? Could a small moon of the planet Endor create such surf? Let’s check it out.

Endor System

First, we have to calculate the gravity on Kef Bir as that influences wave height. The planet Endor is located in a binary star system in the Moddell sector of the galaxy’s Outer Rim Territories, an area rife with hyperspace anomalies. Endor itself is a gas giant with nine moons. One of the moons is the forested moon, also called Endor, where the Battle of Endor was fought in Return of the Jedi. One of the other satellites is the ocean moon Kef Bir. The forest moon’s diameter was 4900 km, 70% the size of Mars. However, the forest moon supposedly had a lighter-than-standard gravity (Wallace and Fry, 2000). The diameter of Kef Bir itself is either 3,725 km (Wookiepedia, Star Wars) or about 4,000 km based on the size of the Death Star 2’s impact in the surface (Bressar, 2020); or about half the size of Mars (6,792 km). With that diameter, if the mass was similar to Mars, the gravity on Kef Bir would be greatly reduced, about 20% of Earth’s.

This is both interesting and important as it is 30% smaller than the planet Thalassa in my book, Songs of Thalassa, which features monster waves at a surf break called Colossus. The waves on Kef Bir looked exactly how I pictured Colossus in my mind, which is why the scene was so stunning. See, waves on low-g planets are super cool, which is why I used them in my novel, because oceanographic theory predicts waves should be bigger and move significantly slower than on Earth.

Waves on Mars

Believe it or not the theory is derived from Mars’s oceans. If you went back 3-4 billion years Mars had an ocean, Oceanus Borealis, that covered about a third of the planet with an average depth of 450 feet (137 m). Research by Dr. John Banfield at Cornell and his colleagues (Banfield et al., 2015) demonstrated that wind blowing across the surface of that ocean produced wind waves, just like on Earth.

But what would the waves have looked like? According to Banfield (and see Choir, 2015)  they were likely large and moved significantly slower when compared to Earth. Since Mars has only 10.7% of the mass of the Earth its gravitational field is only 38% of Earth’s so it is easier to generate large ocean waves. However, gravity also acts to push waves along and determine their speed. Thus less gravity also means slower waves. Since Kef Bir’s gravity was only 20% of Earth’s the waves would have been even bigger. Check these babies out to see what I mean. How big do you think they are?

Waves on Kef Bir

Monster waves on Kef Bir. Scene from Rise of Skywalker, Disney Corporation.

To find out I did some frame grabs of the wave where Rey rode her Skimmer up a wave’s face (I subscribe to Disney+) and I applied a little math. First I calculated the size of the skimmer relative to Rey:

Rey in her 20 ft. Skimmer.

With Rey at 5’6” I calculated the length of the skimmer to be 20 feet (9.1m). Then I calculated the size of the wave as she went up the face using three frame grabs by comparing the wave size to the skimmer size.

First frame grab as she rises up the wave face. From Rise of Skywalker.
First frame grab with skimmer and wave lengths. From Rise of Skywalker.
Second frame grab. From Rise of Skywalker.
Third frame grab. Will she make it? From Rise of Skywalker.

The challenging part is locating the bottom of the wave. If you looks closely there is a smaller wave building in front of the Rey’s wave but I ignored that and focused on the main wave. After measuring three wave heights, the average estimated wave size was 287 ft. (87m). Yikes, yeah. But hold your horses as we’re not done yet. Because we are looking down on the wave it appears larger than it actually is as we are looking at the slope of the wave, not it’s height. Assuming a viewing angle of 20° and applying a little trigonometry the average estimated wave size is 260 ft. (79m)!

Yes, that’s unreal, and much bigger than the largest wave ever surfed on Earth, currently set by Rodrigo Coxa at Nazaré 2017 at 80. ft. Importantly, the size is consistent with what you would expect on the low-g planet of Kef Bir so Disney got it right (although the team should have been bouncing up and down like John Carter on Mars).

What about Thalassa? Yes, the whole reason it is a low-g planet, 20% smaller than Mars, to create a setting for massive waves and the big-wave surf off between Sage (the main character) and her nemesis Milo.. To find out how big the waves are on Thalassa, you’ll have to read the book but they are pretty big.

Rey in the Waves

Rey in her Skimmer. From Rise of Skywalker.
Rey navigating through waves. From Rise of Skywalker.

As to Rey riding giant waves; is that possible? Because she was raised on the desert planet Jakku it is unlikely she had any experience with waves or oceans. So Kef Bir was probably her first encounter with big waves. Could she have realistically ridden those waves with the skill she showed in Rise of Skywalker? Of course, because she’s a badass Jedi and the Force is with her.

References

  3 comments for “Did Rey Skywalker ride a monster 260 foot wave on Kef Bir, the Ocean Moon of Endor?

  1. Grant Roden
    May 10, 2020 at 12:49 pm

    Funny, we were watching that movie last night and we were comparing it to Nazare–and guessed they wave height was about 200ft. Thanks for clarifying the science behind the estimate.
    In this scenario, how would the factors influence trying to duck-dive one of those waves?
    Thank for the Blog!

  2. Geoff Stamp
    May 22, 2020 at 1:17 pm

    The water, the waves were one of the most enjoyable features of a film mostly filled with wrecks and wreckage. Instead of swanning off to the desert, maybe Rey could encourage the humans who lost out to rebuild, or was it Disney’s design to leave us feeling the resistance inherits a few wrecked planets with an awful lot to clear up, oh and of course, a quick return to Ewok-land (a throw-off from Peter Pan’s Neverland), presumably for another teddy-bear binge. Was not convinced by the ending. But that sea: 100%+. Thanks!

    • May 23, 2020 at 7:32 am

      Thanks Geoff. It was a dark movie for sure and I loved the water and waves as well

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