Science Behind the Fiction: How possible is Han Solo's Kessel Run boast?

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May 30, 2018

Lucasfilm's Solo: A Star Wars Story was troubled from its first jump to hyperspace. Rumors, reshoots, and last-minute crew changes fed speculation that the film wasn't going off according to plan. Perhaps that's just as well; it's certainly in keeping with the characters and plot of the film.

No plan survives contact with the Empire, and it's the ability to improvise and overcome that makes characters like Han and Chewie so much fun to root for. From the first time we meet Han in A New Hope, one thing is made abundantly clear: This is a man who can do the impossible. Or at least he wants us to think so. And there is perhaps no greater example of Han's ability to beat the odds (though you should never tell him the odds, kid) than trimming more than a third off the previous Kessel Run record (depending on the source material), completing it in under 12 parsecs, if Han is to be believed.

Since Star Wars first entered the public consciousness in 1977 there has been speculation surrounding exactly what Han meant by this particular claim.

At first glance, it suggests that the Millennium Falcon is fast, but a parsec isn't a measurement of time, it's a measurement of distance. In astronomical terms, a parsec is the distance at which an astronomical unit (the distance between the Earth and the Sun) subtends an angle of one arcsecond. In simple terms, it's a distance of 3.26 light-years and is the standard measure of distance among astrophysicists when discussing the vast distances of the universe.

This puts a peculiar spin on Han's statement. You might be impressed by a friend who claims to have driven a car 100 miles in less than an hour, but you'd be more than a little skeptical if they claimed to make the same trip in under 70 miles. That's essentially what Han has claimed, and it's met, at least by Obi-Wan, with more than a little skepticism.

Since the release of A New Hope, there have been a number of explanations for Han's unusual declaration, and only now, after the release of Solo: A Star Wars Story, do we have a definitive answer. But before we get to the truth as laid out by the new film, let's take the potential explanations in turn.

**Spoiler Alert: there are spoilers for the Expanded Universe as well as Solo: A Star Wars Story below**

A mistake of terms

The most obvious out-world explanation for this exchange is that the lines, as written, were a misnomer. Stan Lee, of Marvel fame, has been known to be pretty upfront about playing fast and loose with scientific terminology. Lee has stated in interviews that he's more concerned with something sounding cool than the real science behind it.

“When I did the Fantastic Four, that was the first of the Marvel heroes, I wanted to give them superpower, but I didn't want them coming from another planet. So I figured, well, I'll have them go up in a rocket ship and they're hit by cosmic rays. I had read about cosmic rays somewhere. I had read the name. I don't know what a cosmic ray is. I wouldn't know it if it hit me. But it sounded good, so we did that," Lee said while speaking with Today. “Then I needed something to make the Hulk the Hulk, so I said, well, I'll have him hit by gamma rays. So he was the victim of a gamma-ray explosion. I know less about gamma rays than cosmic rays. But again, it sounds good."

It's easy to see how George Lucas might have borrowed a page from the same playbook, concerning himself more with the tone of his story than its scientific accuracy. Star Wars is, after all, more fantasy than sci-fi, despite its dressings.

There's some pretty compelling evidence to support this explanation of the 12 parsecs claim. The fourth draft of the script for A New Hope, penned in 1976, includes a note for Ben Kenobi's reaction. It states: “Ben reacts to Solo's stupid attempt to impress them with obvious misinformation."

This, in and of itself, only implies that Han and the Falcon couldn't have trimmed that much distance off the Kessel Run, not that accomplishing a particular route via a shorter distance is inherently impossible.

The real nail in the coffin, the pièce de résistance, when arguing that Lucas simply didn't know or didn't care about astronomical jargon and used the wrong terminology is the 1976 novelization of A New Hope, originally titled Star Wars: From the Adventures of Luke Skywalker.

In this version of the story, the term "parsecs" is replaced with "standard time units," which seems to suggest that, at the very least, the novel's author, Alan Dean Foster, recognized the gaffe and made moves to correct it.

We could leave the speculation here, consider it case closed, but where's the fun in that? Fans have spent decades justifying Han's statements in an effort to make them mesh, and we'd been remiss not to at least glance at the possibilities.

Skimming Event Horizons

Let's assume Han (and, by extension, Lucas) knew exactly what he was saying when he told Luke and Ben he'd trimmed a significant distance off the Kessel Run. How, exactly, could that be done?

This problem was visited in the novels of the Expanded Universe (now Legends), where it was explained that the Kessel Run was a popular route for smugglers running glitterstim, a drug capable of boosting psychic powers, from the spice mines of Kessel.

The standard route ran roughly 18 parsecs and avoided The Maw, a cluster of black holes near Kessel. The standard route, however, was not without its own dangers. Pilots still had to navigate through an asteroid field clouded in a nebula. The Han Solo Trilogy of books by A.C. Crispin tell the story of Han's Kessel Run and explain that by flying closer to The Maw, a route most pilots wouldn't dare to take, he was able to trim the distance and, subsequently, the time of travel.

From a physics standpoint, if Han were able to get close to the many black holes that made up The Maw, without being sucked into their event horizons, he could use their gargantuan mass as a gravity assist, increasing his speed beyond what the Falcon might normally achieve.

Gravity assists are not uncommon in real-world space travel. Human-built craft often use the gravity of bodies within our solar system to push them along their way.

The Voyager spacecraft, the current front-runners for most distant man-made objects in space, used gravity assists several times along the way. Using the gravitational pull of nearby celestial objects is useful not only in reducing the fuel needed for a particular trip but in altering trajectory as well. Even the ill-fated Apollo 13 rescue mission utilized a gravity assist from the Moon, slingshotting around the back side rather than burning fuel to attempt a direct turnabout.

Skirting black holes and using their mass to whip the Falcon through space at faster speeds and shorter distances than ordinary isn't entirely outside the realm of possibility. But all speculation and earlier explanations are moot now that Solo: A Star Wars Story is in the books. The fabled Kessel Run is, at long last, finally a concrete event in the Star Wars mythos.

The Definitive Answer

Solo tells the tale of Han Solo from indentured youth on Corellia, through his term of service in the Empire's infantry, all the way to his meeting with Chewbacca and acquisition of the Millennium Falcon. Central to this story is the famous Kessel Run.

Han's early bid for freedom required a heavy sacrifice. In an attempt to get off-planet, he was separated from his partner Qi'ra and forced to leave her behind. In an effort to save her, Han joined the Imperial forces, where he was ultimately accused of desertion and sentenced to a violent death. Luckily, he met Chewbacca and got himself embedded in a band of miscreants and thieves on an attempt to steal coaxium, an incredibly powerful and equally valuable fuel source.

When the original deal goes belly up, Han and his new (and old) friends must steal unrefined coaxium from Kessel and deliver it to a refinery before it becomes unstable.

After leading an unintentional rebellion on Kessel, sparked by the activist droid L3-37, Han and company have little time to refine the highly explosive coaxium before it goes critical. Adding to their troubles, the Empire, responding to news of the Rebellion, sets up a blockade along the regular Kessel route. Han's left with little choice but to enter the Maelstrom (a stand-in for The Maw of Legends fame), a nebula filled with uncharted black holes, not to mention gargantuan life forms ready and willing to consume anything and everything that comes within their grasp.

This direct route reduces the total distance from 20 parsecs to around 12. The plan almost fails when the Falcon is trapped at the edge of a black hole's event horizon but the crew is able to escape utilizing the navigational expertise ripped from L3's neural matrix (R.I.P.) and more than a little of Han's moxie.

Solo's chain of events rather simplifies the explanation. There aren't many calculations needed and no distortion of space-time required. All that's needed is the simple maxim with which we're all familiar, that the shortest disance between two points is a straight line, even if that line cuts through black holes and giant tentacled space monsters.

Though it's important to note that the very first time Han makes the claim of running Kessel in under 12 parsecs, Chewie calls him out on the carpet. Han replies that the statement is true… if you round down.

So the old suspicions are true. Han truly is a scoundrel and a liar, but that doesn't subtract from his obvious skill, determination, and grit in the face of adversity.

It is, it turns out, possible to complete the Kessel Run in both less time and distance… if you're willing to bend the truth just a little.

Solo: A Star Wars Story is in theaters now.

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