2047. The starship Event Horizon went missing seven years ago and has mysteriously reappeared in orbit around Neptune. In the opening scene, we see the Event Horizon in orbit over a large storm on Neptune. We know that all of the giant planets experience such storms, though they don’t have visible lightning and audible thunder that you can hear in space. The bigger sin is that the storm is visibly rotating. Everyone who has lived in a part of the world that experiences cyclonic storms (hurricanes or typhoons) knows that, even though the wind speeds are really high, cyclones are big. If you were in space, could you visibly see one rotating?
The largest and fastest cyclone observed on Earth (Typhoon Tip, 1979) had peak wind speeds of 190 mph and was 1350 miles in diameter. If we assume the maximum wind speed occurs at the outer radius of the storm (which isn’t true, but we’ll go with it for simplicity) then the rotation time is ~22 hours, which would definitely not be easy to see in a few seconds.
Are storms on giant planets different? They’re certainly larger and have faster wind speeds. I couldn’t find good data for a storm on Neptune, so let’s go to the extreme. The Great Red Spot on Jupiter is ~15000 miles in diameter (on average) and has sustained winds up to 270 mph. That makes the rotation time for the storm ~7.25 days!
Watching the storm in the film, it appears to be rotating at around 3 degrees/sec, so a full rotation would take 2 minutes. Eyeballing the size of the storm relative to the size of Neptune, it appears to be about 5,000 miles in diameter. That means the windspeed would need to be 47,000 mph!
Meanwhile, in Earth orbit, a crew is preparing to go investigate the Event Horizon. They depart from this space station:
The crew get into tanks full of… water? Because once the ion drive starts, they’ll experience 30 g acceleration that will “liquify your skeleton”. They got one thing right here: 30 g is bad. Death becomes likely at ~25 g, at least after more than a couple of seconds. But the problem isn’t your skeleton, it’s your soft tissue. Your skeleton could likely take a fair amount more than that, so long as you don’t impact into something. If you were seated comfortably in a launch chair, your skeleton could probably take several hundred g, but your brain would, technically speaking, turn to goo.
We’re told that they’re in stasis for 6 days. Is that reasonable? Let’s start with acceleration of 30 g. Remember, they need to slow down too or else they’ll shoot right past Neptune. 1 g is 9.8 m/s^2, so 30 g is 294 m/s^2. If they accelerate at that rate for one day, they’ll be traveling at 25 Million m/s, or about 56 Million mph (about 8% the speed of light). Neptune is 2.8 Billion miles away, so at that speed, it would take about 2 days to get there. Assuming the ship can also decelerate at 30 g, then add another day for that, put some cushioning in for the rounding errors and oversimplification, and 6 days isn’t too bad! Way to go movie! (If they accelerated at a constant 30 g for 6 days, they’d be traveling at 1/2 the speed of light by the time they got to Neptune.)
After the trip to Neptune, we learn the secret of the Event Horizon: it was a ship designed for faster-than-light travel. It would accomplish this by creating a singularity (a.k.a. black hole) that would curve spacetime in exactly such a way as to allow you to pass from point A to point B instantaneously. There’s some ridiculous jargon about focused gravitons and rotating magnetic fields, but we’ll let that slide.
For some reason, the Event Horizon is now inside the big storm on Neptune. I’ll come back to this particular topic again: spacecraft, especially those of the spindly framework variety, are not made for passing through the atmospheres (or oceans!) of planets. I’m looking at you, J.J. Abrams.
From here, the movie descends into a nightmarish gore-fest, as it turns out the gravity drive has opened a porthole to a dimension of pure evil rather than to Proxima Centauri as they intended, so science goes out the airlock along with the remains of several of the crew. The film ends with a black hole being set loose inside the upper atmosphere of Neptune, which presumably will eventually devour the entire planet. Those “Pluto is SO the 9th planet!” folks are not gonna be happy about this…
Let’s tally up the score: Travel time to Neptune: correct but inconsequential. Storms on Neptune: visually striking and completely inaccurate. Singularity: leads to hell.