#2. Gravity Won't Yank You Out of Orbit Like a Magnet
Pop quiz: What happens when a spaceship in high orbit loses its thrust? According to sci-fi logic, the ship will immediately drop like a rock toward the surface of whatever it's orbiting, just like General Grievous' ship in Revenge of the Sith or the Enterprise in Star Trek into Darkness. (If it seems like we're picking on Star Trek and Star Wars too much, it is only because we love them. This is the nerd version of pulling pigtails on the playground.)
Darrin Klimek/Digital Vision/Getty Images
"Good luck trying, assholes. Why do you think I wear my hair like this?"
Someone way smarter than us already did the math on that Star Trek scene we mentioned above, and it turns out that the dead-in-the-water Enterprise would actually have taken about 80 hours to fall into Earth's atmosphere from that height. It's understandable why that didn't make the movie: Two solid work weeks of watching Sulu polish his sword before crashing into the planet might derail the pacing a bit.
Much to the dismay of your average sci-fi space battle scene, gravity isn't a giant invisible rubber band that snaps you to the planet's surface like a paddle ball as soon as you stop resisting it. And not only would the Enterprise's plummet have been more of a leisurely descent for much of the way, but if the crew had actually managed to achieve orbit before losing power, the ship wouldn't have fallen at all. Not one bit of thrust is required to remain in a stable orbit once you're there -- just ask Vanguard 1. One of the first artificial satellites ever launched, it's still happily floating more than half a century later.
"Log 12837: little lonely, but otherwise happy."
Well, OK, maybe we're embellishing a bit. Orbits do eventually decay. Vanguard 1 was originally expected to orbit for 2,000 years, but thanks to greater-than-expected effects of atmospheric drag, that estimate got knocked down to a mere 240. So the next time you're watching a thrilling space saga and the brave Captain Beef Thickpack says, "Without our engines, our orbit will decay, crashing us into the planet below!" just mentally append "in about 10 generations."
#1. Zero Gravity Does Not Equal Slow Motion
If 2001: A Space Odyssey taught us anything, it's that Siri will one day murder us all. Oh, and also that moving around in space is like swimming through an infinite vat of invisible pea soup. Everything from space walks to cinematic spaceship flybys to Borg death-stomps will happen in the slowest of sloooow mooootions.
We'll even jog slowly, whatever that means.
Why would things move slower in space, unfettered by the fascist repression of atmosphere and gravity? In fact, they actually tend to go faster. Since there's a near complete lack of external forces, as long as a spacecraft is firing its thrusters, it's accelerating (up to a certain extent, of course). That's why rocket scientists use the concept of delta-v -- basically saying, "How much fuel are we going to have to burn to pull that shit off?" Spacecraft are limited not by surrounding forces, but by how much fuel they have left and how tired someone at mission control is of holding down the GO! button.
So why do actual astronauts look like they're constantly pantomiming through peanut butter? It is solely the fault of the astronomical assload of gear they have to wear. You go suit up in an incredibly bulky, insanely expensive spacesuit (you break it, you buy it ... and, uh, you also die), and then see how sprightly you are.
That thing weighs a ton. Well, it weighs nothing, but you know what we mean.
And if you've ever seen video from inside the space station and wondered why everybody looks like they're running in a dream, that's not because quick movements are impossible. They're just not advisable. Jump-kicking across the length of the ISS might sound awesome, but the only thing absorbing all that force when you reach the other side is your own squish-filled meatsack. Even if you survive unscathed, all of that seriously expensive and utterly vital equipment is now smashed to bits.
The slow movements you see in real space footage aren't the astronauts wading through some weird, invisible space jam; it's simply them being very, very careful. But we're pretty sure every astronaut has jump-kicked across the ISS at least once, just to get it out of their system.
Related Reading: Did you know space holds a gigantic liquor cabinet big enough for God? And were you aware that Zambia had a space agency? The story is more ridiculous than you can imagine. We've got crazier stories than that, though -- check out the most badass things ever done in space.