After Earth has been slammed by critics for many reasons, from Jaden Smith‘s lackluster performance to the plodding pace to the shoddy CG work. But Buzz Aldrin has to be one of the few folks whose grievances stem from personal experience with outer space travel.

While the astronaut stated that he enjoyed the M. Night Shyamalan-directed adventure overall, he complained that its space scenes were unrealistic. That shouldn’t come as a shocker to anyone — Hollywood films, sci-fi or otherwise, are rarely accurate depictions of real life — but if you’re curious to find out exactly what his point of contention is, hit the jump to keep reading.

In a conversation with the Huffington Post, Aldrin explained that his issue was largely with how loud the space scenes were. “There was a lot of noise. In space, you don’t get that much noise,” he said. After Earth is far from the only picture to make that error; loud explosions and crashes are a staple of sci-fi film, natural laws be damned. But that doesn’t mean they’re factually correct. As Aldrin pointed out, “noise doesn’t propagate in a vacuum.”

The characters’ action-packed stay on the foreign planet (well, foreign to them) didn’t mesh with Aldrin’s memory of stepping on the moon, either. “The place was just totally lifeless,” he recalled. But of course, visiting a desolate moon and encountering actual non-Earth life are two different things. “I hope the aliens are more peaceful than they are in this film, wherever they are,” he said jokingly.

Despite those issues, Aldrin actually seemed to like the film more than most, praising Will Smith and Jaden Smith’s father-son dynamic and the futuristic set design. “The scenes of the cities were really remarkable,” he said.

As for where entertainment junkies can turn to get a little more “science” in their science fiction, Aldrin had one suggestion: “Arthur C. Clarke added a bit of reality to the genre with the (function) of the ship and people flying out in space on a mission.”

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