If there isn't an "upside down" in space, then space battles in movies are unrealistic when the ships are always upright when they confront each other.

There are a few things about space battles that most sci-fi really gets wrong.

First is that, in the absence of a nearby planet to orbit newton's first law is on full display. if you accelerate to 1000 mph in a particular direction you'll continue to move that direction no matter which way you're facing until you accelerate in the opposite direction another 1000 mph. In effect this makes all attacks "strafing" attacks as there's no need to move in the same direction you want to fire. For instance, in star wars during the death star trench scene, Luke could have simply turned to face Vader and they could have fought face to face without their trajectory changing.

Secondly, if you ARE orbiting a planet then as per newton you're being acted on by an outside force. while you can still turn to face your opponent no matter what direction you're headed, your trajectory is actually constantly changing to follow the arc of your orbit. In practice this means that objects in the same orbit (same distance from the planet and moving at the same speed) appear motionless relative to one another while objects at different altitudes or that are moving at slightly different speeds relative to the planet appear to drift apart. For example in Gravity the whole 90 minute countdown to destruction made no sense. The 90 minutes comes from the fact that the space station is at an altitude that orbits the earth every 90 minutes. While its possible to be struck by debris blown out of its original orbit, if the space station and the debris orbit the earth every 90 minutes they should appear relatively motionless to one another. It is possible that the debris field could have struck the station the first time if the stars aligned, but doing so would mean its orbit was different from that of the station's and they wouldn't likely contact each other again for years if ever.

/r/Showerthoughts Thread