The Speed of light and distance.

[OrbitalConfusion]

Im going to give a hypothetical scenario here.. Please, just go with it.


Im on a planet looking at the night sky that is oh say 300,000 light (or more if need be to see dinosuars!) years from earth. I walked down to my local Space mart earlier and purchased a snazzy ultrahigh powered telescope. This telescope is so powerful I can see the features on earth as good as what our mapping sat's do perhaps even better.

Would I see Dino's walking around? Yes, yes I would.

If I hopped into a space ship and traveled at the speed of light or close too it with my telescope i would see the earth in "fast-forward" like on a VCR. ok cool.

So my question is this. The furthest stuff we have viewed thus far... Is there a fair enough probability that some of the stars we "see" are actually not there anymore? As in we are waiting for the post supernova light to reach us?

Could things look much differently as you approach the vicinity of these things?

 

[RisingFury]

Dinosaurs went extinct 65 million years ago, so you'd have to be at least 65 million light years away.

And to answer your question: Yes, things are actually different at the edge of the observable universe now, than they were when light left those objects.

They're not even there anymore. Keep in mind that the universe is expanding. The further away an object is, the faster it moves away from us. The objects at the edge of observable universe have had 13 billion years to travel even further out.

And yes, quite a few of the stars that we "see" don't exist anymore. Not even the galaxies do. They merge over time with others, some get ripped apart and some die of old age when there are no more new stars being born inside them.

 

[Quick_Nick]

Sometimes they go from there to 'not there' while we're watching.
http://deepbluehome.blogspot.com/2011/02/illustrated-crab-nebula-seen-through.html

 

[Artlav]

Anything we see in the sky is history.
The Sun of ours might have just exploded, but we won't know anything for 8 more minutes.
The stars we see are not where they appear, and are probably even look different.
The shape of our galaxy looks different from reality - the further away, the more off it is.

Actually, the last line makes me wonder - is there an observable distortion in the shapes of spiral galaxies that we see nearly edge-on?
Stars in there do move slowly, travelling only 0.04% of the circumference in the time light crosses one (1e5 ly diameter, 250 million years per orbit?), is that enough to be observed?

 

[statickid]

Anything we see in the sky is history.
The Sun of ours might have just exploded, but we won't know anything for 8 more minutes.
The stars we see are not where they appear, and are probably even look different.
The shape of our galaxy looks different from reality - the further away, the more off it is.

Actually, the last line makes me wonder - is there an observable distortion in the shapes of spiral galaxies that we see nearly edge-on?
Stars in there do move slowly, travelling only 0.04% of the circumference in the time light crosses one (1e5 ly diameter, 250 million years per orbit?), is that enough to be observed?

I think the main problem is resolving the actual stars. Its like taking photos of smoke and trying to figure out whether or not a certain smoke particle moved exactly where you predicted.

 

[OrbitalConfusion]

Sorry, about getting the time frame with the Dino's wrong. I think I had, well I did have a bonafide brain-fart. I was doing a bunch of reading and the 300,000 number came from, well it doesnt matter.

Ok, so the further out from earth you travel how would you keep you bearings? You cant depend on stars... I guess you could stop every so often and do a survey then continue on you way... But I think it would make navigation a nightmare. Or just impossible.

 

[garyw]

Ok, so the further out from earth you travel how would you keep you bearings? You cant depend on stars... I guess you could stop every so often and do a survey then continue on you way... But I think it would make navigation a nightmare. Or just impossible.

You'd use pulsars.

 

[OrbitalConfusion]

Gary, I may not know you, but thanks!! I honestly try my best to answer my own questions by searching, but this is a direction I would have never thought to look. You so got a thank you click from me!