An interplanetary coordinate system

On earth, we use a simple but effective coordinate system which determines position unambiguously on the surface (GPS achieving accuracy within 1 meter, which speaking as an engineer, is a remarkable feat in of itself).

For example, Greenwich, England is located at coordinates 51.4800° N, 0.0000°. This disregards tilt of the earth, position around the sun, minor gravitational directional changes due to the pull of the moon, etc. because they are not relevant.

My point is that should we one day inhabit one or more planets outside our solar system, we'll need a new unambiguous system to identify coordinates of the planet in 3d space.

A 3d coordinate system with an x, y, and z coordinate would be relatively impractical since the position of the planet in question would be constantly changing position. There are several factors that come to mind to take into consideration:

• Position of the star it is orbiting
• Any local moons that may alter it's position slightly.
• The tilt of the planet at any given moment (unlike our current system which needs not consider the current tilt of the planet, you would need to know the current tilt in order to find the proper 2d planetary coordinates)

Like most good systems, it must have the following qualities:

• Be precise, in this case lets say within a kilometer of the destination.
• Be concise. Minimize the amount of information you need to provide, in this case in order to unambiguously find the position of the planet
• Be accurate also in the near future. Coordinates which are established on earth must still unambiguously be valid by the time a ship arrives (lets say remain within a kilometer of the destination within 100+ years time)

Assume there are no adverse space-time effects to consider (which would likely make an accurate and practical interplanetary coordinate system nearly impossible).

Assume that we will have computers and thus you do not have to provide information that could otherwise be calculated or remains relatively static (within 100 years time stays the same). For example, given a star's 3d coordinates and angle, a computer would load the planet's distance from the sun and be able to determine roughly where that planet would be, without having to include it in the coordinate system.

posted almost 10 years ago

Neil‭

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