How do direction work in space because north,east,west and south are bonded to earth? How does a spacecraft guide itself in the unending space?
In: Physics
Easy, the enemy’s gate is “down”. I’m not a space engineer of any sort, but I can at least talk about the math that’s helpful here (linear algebra).
When you are walking around, you can talk about how things are *in front/behind* of you, *to the (right/left) side* of you, or *above/below* you. If you want to be clever, you can mix the descriptions too: “enemy ship at 2 o’clock!” means something is mostly to your right, but also a bit in front of you.
When you’re talking to someone else that isn’t facing the same direction, you can’t just use the forward/right descriptions anymore, so you have to pick something both of you understand. A nice one is to align to the Earth with North/East/South/West. Or, if you know what direction they’re facing, you may choose to use their perspective instead (“turn right on Maple, then turn left on Jefferson…”).
To give directions, you only need to define the three basic directions “up”, “right”, and “forward” and go from there. The third can be derived from the first two, so really you just need two of them. Usually you use some sort of reference point(s), maybe a star or a planet or your own spaceship, whatever.
ELI25 note: a set of *n* directions for an n-dimensional coordinate space is called a *basis* space, and requires *n* orthogonal vectors. Converting from one basis to another is very easy with linear algebra. With as few as three points that aren’t all on the same line (e.g., center of the sun, North Pole of the sun, some other star) you can create a full basis because of the neat property that the cross product of two vectors is always orthogonal to both input vectors.
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