Astronomy questions (edit: questions answered Thanks guys!)

[genshou]

Awesome.

 

[Pbartender]

(Pulsars wouldn't be useful because you have to be aligned with their axial jets to see them. From any other point in the galaxy, chances are you won't see the ones that we can see from earth.)

Good point... I'd forgotten about that.

 

[Umbran]

(Pulsars wouldn't be useful because you have to be aligned with their axial jets to see them. From any other point in the galaxy, chances are you won't see the ones that we can see from earth.)

The Sun sits relatively close to the galactic equatorial plane. So long as the pulsar also sits mostly near the plane, if its jets sweep us, they probably also sweep other large portions of the plane. And it isn't like the jets are narrow at interstellar distances. While you are correct that they would be somewhat less likely to be found, their distinctive rates make them easy to uniquely identify, which is terribly useful in this case.

You couldn't rely on things like quasars, which only have life-spans of 10 million years or so.

The current estimates for net quasar lifespans generally lie between one million and 100 million years. While 10 million lies in the middle of that range, in terms of order of magnitude, the wide margin of error there means they may still be useful. In this case, failure to see them can give you useful information - it tells you are outside a certain volume of space, and that helps you figure out what else you might look for...

After a bit of thought, though, I've realized that most of this is moot - in a sense, where you are in realspace relative to Earth is unimportant unless you travel through normal space to get there. If you're using wormhole or other dimensional travel, what matters is the distance through that other dimension that matters. Depending on your travel methods, it could be easier and quicker to get to the galactic core than to get to Alpha Centauri.

 

[FoxWander]

I only have a couple of things to add as I'm not a big astrology buff or terribly fond of math. But I do know what would make an interesting story. I think the idea of one of the characters having the sculpture WayneLigon linked to (this one but more accurate) and then using it to illustrate where they are would be funny, in an "OMG! We are so screwed" kind of way.

Also, putting them at M4 or one of the clusters Pbartender mentioned that are just above the galactic disc would be both immediately shocking (in terms of "we're not in Kansas anymore" effect) and probably more than a little terrifying! Just imagine it- you look out your spaceship porthole and see thousands/millions of stars 'below' you and 'above' you, something completely different. Mostly blackness but spotted with a multitude of bright points. And then you realize that each of them is a galaxy itself! Check out the Hubble Deep Field image to get an idea what it would look like. Wonderous and terrifying at the same time, I would think.

 

[Pbartender]

Also, putting them at M4 or one of the clusters Pbartender mentioned that are just above the galactic disc would be both immediately shocking (in terms of "we're not in Kansas anymore" effect) and probably more than a little terrifying! Just imagine it- you look out your spaceship porthole and see thousands/millions of stars 'below' you and 'above' you, something completely different. Mostly blackness but spotted with a multitude of bright points. And then you realize that each of them is a galaxy itself! Check out the Hubble Deep Field image to get an idea what it would look like. Wonderous and terrifying at the same time, I would think.

What they see would probably look a lot like this...
http://www.wallpaperbase.com/wallpapers/space/galaxy/galaxy_13.jpg
...except it would be a little bit more flattened. And it would fill half the sky.

 

[BiggusGeekus]

What they see would probably look a lot like this...
http://www.wallpaperbase.com/wallpapers/space/galaxy/galaxy_13.jpg
...except it would be a little bit more flattened. And it would fill half the sky.

Are those galaxies or stars I'm looking at there?

(I mean, aside from the Miky Way)

 

[Matt Black]

The current estimates for net quasar lifespans generally lie between one million and 100 million years. While 10 million lies in the middle of that range, in terms of order of magnitude, the wide margin of error there means they may still be useful. In this case, failure to see them can give you useful information - it tells you are outside a certain volume of space, and that helps you figure out what else you might look for...

The problem is that even if you did happen to look at a known quasar, you would never recognise it. Quasars tend to have pretty generic spectra, and those spectra are highly dependent on the viewing angle (with obscuration and relativistic beaming of jets). Quasars are also highly variable, and their lifecycles are very poorly understood. So a full-blown radio quasar observed from Earth might be a piddling emission line galaxy when observed from another angle/time.

After a bit of thought, though, I've realized that most of this is moot - in a sense, where you are in realspace relative to Earth is unimportant unless you travel through normal space to get there. If you're using wormhole or other dimensional travel, what matters is the distance through that other dimension that matters. Depending on your travel methods, it could be easier and quicker to get to the galactic core than to get to Alpha Centauri.

Except that, regardless of how you travel between two points, light still has to take the realspace route. If you were to teleport to the Virgo cluster, you would be seeing a universe that was 50 million years older in one direction, and 50 million younger in the other direction.

Actually, you would see the same age universe from directions orthogonal to your travel vector - which would describe a ring of space. If you were to look at sufficiently distant quasars along this ring you should see them at the same age and viewing angle as from earth. They'd have to be distant enough that the difference in viewing angle was 'very small'. Unfortunately, that might negate their use in triangulating your position. However the plane of the ring would at least tell you that the Earth was in one of two directions. Flip a coin and start travelling...

 

[Umbran]

So a full-blown radio quasar observed from Earth might be a piddling emission line galaxy when observed from another angle/time.

Yes. And in the differences, there is information, too. So, if you can find the thing and identify it for what it is (say, by proximity to other objects), you know some things about your new position. It may be that you can't identify them. But there are few to no other landmarks out at that distance, so you might as well try.

Except that, regardless of how you travel between two points, light still has to take the realspace route. If you were to teleport to the Virgo cluster, you would be seeing a universe that was 50 million years older in one direction, and 50 million younger in the other direction.

Yes. The distance from you to your chosen landmark needs to be large compared to the distance you've covered. If you jump to Alpha Centauri, you don't go trying to use Jupiter and Saturn as your landmarks, even if you can see them.

Given the stipulated computers, figuring out the changes in stellar or galactic position you'll see resulting from superluminal travel can be handled.

But again, I note that if your mode of travel is not through normal 3-space, your 3-space position doesn't matter much anyway.

 

[Mustrum_Ridcully]

An interesting side question? How long would actually take to make the neccessary observations to detect certain starts, galaxies or quasars?
How long are Hubble and other observation systems active now? How much of space have we seen?
How long did it take us to find a specific and interesting star?
If, for example, all the telescopes in the world neeed 50 years till we detected and identified a specific, unique pulsar, how long wouldn it take us to detect and identify the same one if we were somwhere else? Would it also take 50 years (assuming we took "all the telescopes in the world" with us)?

How much interesting objects did we find by pure luck, because some scientists decided to point their telescope at a specific direction for a sufficient amount of time to see the "Interesting Object"?

 

[Pbartender]

Are those galaxies or stars I'm looking at there?

Mostly stars. If you see something that looks like a smudge or smear of light, then that's probably another galaxy.

(I mean, aside from the Miky Way)

Psst... that's not the Milky Way