Space Directions

[Gawian]

Travel across an entire galaxy should surely require a system of direction with more than 2 axis though? Because not all star systems are on the same plane? There is... for lack of a better understanding of the galaxy, a bit of a height discrepancy.

N/E/S/W only covers 2 axis.

 

[Vertigo]

Jack Campbell has quite a neat way of doing it when in a stellar system turning towards the star is to starboard and port is turning away from the star. And then up and down refer to the ecliptic plane of the system - I can't quite remember how they decide which is which on that Possibly just an arbitrary decision made when entering the system, so long as everyone is in agreement then that should work. Seems like a simple effective way of doing it.

 

[Venusian Broon]

Travel across an entire galaxy should surely require a system of direction with more than 2 axis though? Because not all star systems are on the same plane? There is... for lack of a better understanding of the galaxy, a bit of a height discrepancy.

N/E/S/W only covers 2 axis.

Which is why I said you should also have an 'in/out' direction relative to the centre of the galaxy as well if you are going to use this.

It would be probably be better to use some sort of spherical geometry - so distance r from the centre and two angles, but three-dimensional spherical geometry tends to make most people's heads throb painfully.

 

[The Ace]

For combat, what's wrong with the, "Clock," system, with 12 o'clock being directly ahead ?

"Six o'clock high," needs little explanation.

 

[ThomasG]

I particularly don't like the use of clock directions, since that would only be based on a 12 hour Earth Clock.

 

[TheDustyZebra]

Travel across an entire galaxy should surely require a system of direction with more than 2 axis though? Because not all star systems are on the same plane? There is... for lack of a better understanding of the galaxy, a bit of a height discrepancy.

N/E/S/W only covers 2 axis.

I'm glad it's not just me.

 

[Mirannan]

Jack Campbell has quite a neat way of doing it when in a stellar system turning towards the star is to starboard and port is turning away from the star. And then up and down refer to the ecliptic plane of the system - I can't quite remember how they decide which is which on that Possibly just an arbitrary decision made when entering the system, so long as everyone is in agreement then that should work. Seems like a simple effective way of doing it.

AFAIK the ecliptic plane of a system is the orbital plane of the principal orbiting body in the system. I suppose the principal body would have to be pre-decided. Some possibilities:

If there is only one inhabited planet, use its orbital plane. Similarly, if there is more than one use the one with the most population. (This currently applies to the Sol system, of course.)

If there are no inhabited planets, use the orbit of the orbiting body with the largest mass for reference. This will probably be a gas giant or brown dwarf - if indeed there can be any other planets in a solar system including a brown dwarf, which question I don't know the answer to and I doubt anyone else does either.

If there is no clear winner in this respect, use the equatorial plane of the primary.

This does, of course, mean that on arriving at an unexplored solar system the ecliptic plane will be unknown/undefined. In such a case, use the position and velocity of the arriving ship as a provisional reference point/plane. (Assume the ship is travelling in the ecliptic.)

 

[Vertigo]

I think that on entering a new system computers combined with observations would be able to very rapidly establish the ecliptic plane of the system; as Mirannan suggests the only issue would be deciding which planet to use as a reference.

Instead of the ecliptic, which is specific to and different for each planet in the system, I think the 'invariable plane' of the system might be more correct, which is based on the total angular momentum of the entire system. But picking one planet and using its orbit to determine an agreed ecliptic for that system is probably going to be a lot simpler.

Since this is purely something to use as a reference an alternative would be to use the star's equatorial plane - that is the plane perpendicular to the star's axis of rotation. something that should be relatively quick and easy to determine from observations.

 

[SilentRoamer]

Jack Campbell has quite a neat way of doing it when in a stellar system turning towards the star is to starboard and port is turning away from the star. And then up and down refer to the ecliptic plane of the system - I can't quite remember how they decide which is which on that Possibly just an arbitrary decision made when entering the system, so long as everyone is in agreement then that should work. Seems like a simple effective way of doing it.

Things could get a little confusing in a binary star system!

 

[Vertigo]

Things could get a little confusing in a binary star system!

Very true!

But I suspect the two suns would orbit one another in something very close to their respective equatorial planes. Unless one has been captured at a later date the process of formation from a single accretion disk makes that most likely. Also one star is generally going to be the dominant one and that is the one that would be used as a reference.

 

[SilentRoamer]

Very true!

But I suspect the two suns would orbit one another in something very close to their respective equatorial planes. Unless one has been captured at a later date the process of formation from a single accretion disk makes that most likely. Also one star is generally going to be the dominant one and that is the one that would be used as a reference.

When considered logically the sort of distances required would pretty much allow you to treat the binary system as a single point of reference with a single baryonic centre. Just one gravity well as long as you stay outside of their respective orbits is enough to deal with!

You are right in most instances one star is going to be larger and also there is likely to be material interchange between the two so you wouldn't want to be between them both!

 

[Vertigo]

Though I suppose even that depends on whether they are a close or distant binary pair.

 

[SilentRoamer]

Though I suppose even that depends on whether they are a close or distant binary pair.

Also true. Funny thing is some of the binary or even multiple systems have orbits that exceed human timeframes - millennial long orbits anyone?!

 

[SilentRoamer]

For me any future spatial directions fall into two categories:

1. Space fantasy (does not take into account relativity at all.
or
2. Science Fiction (where there is an attempt to account for relativity and its effects)

With regards to 1 you can do whatever you like as long as it is consistent and doesn't cause the ready to break ranks with the text. Think Peter F. Hamilton.
With regards to 2 you have to play by the rules of relativity - the speed of light is a constant and approaches towards the speed of light slow time sufficiently for there to be very noticeable effects.

With regards to directions and standard military phrases etc. being used then I would argue this is just window dressing and as long as it is consistent the reader should not question it.

TLDR - Consistency is king whenever explaining or ascribing to something not currently possible.

 

[Steven Sorrels]

Though I suppose even that depends on whether they are a close or distant binary pair.

Now imagine the headache I've got, as I have a system with a 2-1 trinary system (close binary pair with a single star orbiting the pair). Talk about some wacky physics!

 

[Vertigo]

Now imagine the headache I've got, as I have a system with a 2-1 trinary system (close binary pair with a single star orbiting the pair). Talk about some wacky physics!

Think I'd go find a simpler system to write about!

 

[Steven Sorrels]

Think I'd go find a simpler system to write about!

I like the challenge

 

[Dennis E. Taylor]

Now imagine the headache I've got, as I have a system with a 2-1 trinary system (close binary pair with a single star orbiting the pair). Talk about some wacky physics!

Just use galactic coordinates. "Galactic north" means one thing, "Stellar north" means another.

 

[Ursa major]

2-1 trinary system

I expect the navigator, on being asked to sort this out, might hit the bottle (specifically Stellar à trois...).

​

 

[Parson]

Now to touch on one of my pet peeves. --- Space Combat is not the same as a atmospheric fighter dog fight. Even at speeds which make inter-planetary flight feasible, to say nothing of speeds best described as 1% of light etc. there would be little time for evasive actions. Most combat would be blink of an eye fast. Probably completely computer directed. No time (and if the speed of light is not ignored) and no ability to get information to another fighter for them to make use of it.