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?

Question

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

Answer 1

Currently we map objects in the sky using polar coordinates. Two angles and a distance.

Usually we use Earth as the centre point (in fact the viewers position on earth) and we work out the angle the object is from the centre line of the sky (that we define) and then the angle off the horizon.

This is declination and right ascension.

It doesn’t make much sense for an interstellar space ship to use earth as the centre point. So we might use the centre of the galaxy. Then define 0 degrees as the line through the sun.

So the solar system would be at 0°,0°,25kly

Changing direction would also likely use angles. Similar to how boats do it. Change angle a by x° and angle b by y°.

I don’t know how actual space craft do it but there it’s precedent in fiction with star trek. At the end of an episode the captain might command the helm to set a course 120 mark 43. That’s your two angles relative to something (the ship, the galactic plane or something)