"Captain America: Civil War" will bring together the Marvel Cinematic Universe's handful of heroes in an internal conflict that threatens to tear apart the Avengers for good. Captain America (Chris Evans) and Iron Man (Robert Downey Jr.) will be going toe to toe, Vision (Paul Bettany) will face off against Scarlet Witch (Elizabeth Olsen), Black Widow (Scarlett Johansson) will trade blows with Hawkeye (Jeremy Renner), and so on and so forth. But one hero who won't enter the fray is Thor (Chris Hemsworth), who left Earth at the conclusion of "Avengers: Age of Ultron."

Now the reason Thor left is because he unknowingly picked up a trail that leads back to the MCU Big Bad Thanos (Josh Brolin). However, Downey Jr. had a much simpler, much more hilarious explanation for his absence.

The above clip comes from Joss Whedon's first "Avengers" movie, and it doesn't exactly show Hemsworth's hammer-wielding skills in the most positive of lights. The funny GIF reveals to fans how light the actual Mjolnir prop is. Hemsworth bobbled the fabled hammer like a wide receiver struggling to haul in a touchdown catch; not exactly a great look for the God of Thunder. If Thor can't handle his main weapon, no wonder the Avengers wouldn't let him come to "Civil War!"

But there is a real reason why Hemsworth/Thor will not be showing up in "Civil War," and it has little to do with bobbling hammers. Thor's journey to research the Infinity Stones in the MCU will lead him directly into his trilogy ending film, "Thor: Ragnarok," which is expected to start filming this summer.

Not only that, he'll also be joined by Mark Ruffalo's Bruce Banner/Hulk. This effectively eliminates the two strongest Avengers from the Earth-centric struggle in "Civil War" and avoids unbalanced team lineups while also setting up a grand space adventure for both characters. "Ragnarok" is one of Thor's most popular stories in the comic books, and it's important to separate that arc from "Civil War."

"Captain America: Civil War" will finally arrive on May 6. "Thor: Ragnarok" will hit theaters on Nov. 3, 2017.