There's a moment in the original "Star Wars" film that has left some viewers—those who know their scientific units—puzzled for quite some time. Han Solo is showing Obi-Wan Kenobi his starship, trying to convince the Jedi of its speed. "You've never heard of the Millennium Falcon?" he says. "It's the ship that made the Kessel Run in less than twelve parsecs."

That sounds awfully fast. But the parsec is a unit of distance, not time. It's equivalent to about 19 trillion miles or 3.26 light-years. How could a hot-shot pilot like Han make such a rookie mistake? Was this a "Star Wars" blooper, a deliberate trick, or the truth? There are three possible explanations.

1. George Lucas Made an Error

The most obvious explanation is that George Lucas didn't do his research. Many sci-fi universes have their own invented time units, such as the microts (seconds) in "Farscape" and the yahrens (years) in the original "Battlestar Galactica."

"Parsec" sounds vaguely like "second," so maybe Lucas intended it to be an exotic-sounding time unit that didn't imply any particular length of Earth time. He simply missed the fact that a parsec is a real unit of measurement.

One could argue that, within the "Star Wars" universe, a parsec is a unit of time. The Expanded Universe, however—as depicted in the film's sequels, prequels, and spin-off comics, books, and video games—establishes time units with the same names as their real-life counterparts.

2. Han Solo Lied

Another possibility is that Han Solo was just making stuff up. He had a price on his head and needed money fast—and here were two apparent yokels in need of a ride. Although Luke Skywalker claimed to be a good pilot, Han probably thought he was bluffing to bring the price down.

By making a seemingly nonsensical claim, Han might have just been testing his potential customers. If they bought the story, he could assume they were ignorant about space travel and try to charge them more.

The incredulous face Luke makes in response to Han's claim might support this theory. For what it's worth, that's also how George Lucas explains the line. Like the previous explanation, however, this interpretation is not supported by the Expanded Universe, which suggests that Luke truly was a novice pilot.

3. Han Solo Took a Shortcut

The Expanded Universe puts forth the most interesting and thorough explanation of the parsec problem: the Kessel Run was normally an 18-parsec route. A popular travel route for smuggling operations, the Kessel Run went around the Maw, a cluster of black holes.

Han's claim to have made the Kessel Run in less than 12 parsecs was therefore not just a boast about his ship's speed but also a boast about his skills and daring as a pilot. Han shaved a third of the distance (and precious time) off the normal route by flying dangerously close to the black holes.

This explanation is detailed in A.C. Crispin's Han Solo Trilogy. In "At the Crossroads: The Spacer's Tale," the bounty hunter BoShek beats Han's record, although the feat isn't as impressive since the hunter doesn't have any cargo in tow.