Stars and Galaxies Question

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This is probably quite a basic question but my mind has been ignited by the recent stargazing programs on the bbc so...

Does every star have to be associated with a galaxy? For example, when looking through a telescope you see either individual stars or spiral galaxies - when looking at these with the naked eye then they're virtually indistinguishable - so does that mean that every lone star visible is part of our galaxy?

So if that's the case then the space between galaxies is just literally astronomically almost unfathomable.

The space between stars in the milky way is vast but I'm struggling to get my head around the distance between galaxies.

If what I question above is true then there are huge lengths of space out there with nothing whatsoever in for millions and millions of miles.
 

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  • #2
Janus
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This is probably quite a basic question but my mind has been ignited by the recent stargazing programs on the bbc so...

Does every star have to be associated with a galaxy? For example, when looking through a telescope you see either individual stars or spiral galaxies - when looking at these with the naked eye then they're virtually indistinguishable - so does that mean that every lone star visible is part of our galaxy?
The individual stars that we see are in our galaxy. That is not to say that there cannot be stars outside of our galaxy (we have in fact seen stars that are traveling too fast to remain in our galaxy), but they would be too faint to see for the most part. We do know that there can't be too many, or they would tend to increase the background radiation of the night sky.
So if that's the case then the space between galaxies is just literally astronomically almost unfathomable.

The space between stars in the milky way is vast but I'm struggling to get my head around the distance between galaxies.

If what I question above is true then there are huge lengths of space out there with nothing whatsoever in for millions and millions of miles.
Millions and millions of miles is would better describe the distances between planets of the Solar system. Galaxies are separated by millions of light years, with a light year being ~6 trillion miles.
 
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It looks like a mind-bender, but you have to look at the big picture. A really really big picture. If you can accept that 99.8% of the stars we can see with our naked eye are in our own galaxy, and that the stars in other galaxies appear as a couple of bright ones because they are that far away, you can start to make sense of it. Visualize yourself leaving the earth and flying past the stars and into deep space between the galaxies - The further away from the milky way you go (which is huge to start with) the stars become closer and closer together and the milky way gets smaller until you are flying into Andromeda, the closest galaxy to us, but in this fantasy you're flying at a few hundred times the speed of light, so spread the time out a little. That is how I make sense of things. And by the way, I enjoyed the stargazing live episodes too.
 
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This is probably quite a basic question but my mind has been ignited by the recent stargazing programs on the bbc so...

Does every star have to be associated with a galaxy? For example, when looking through a telescope you see either individual stars or spiral galaxies - when looking at these with the naked eye then they're virtually indistinguishable - so does that mean that every lone star visible is part of our galaxy?

So if that's the case then the space between galaxies is just literally astronomically almost unfathomable.

The space between stars in the milky way is vast but I'm struggling to get my head around the distance between galaxies.

If what I question above is true then there are huge lengths of space out there with nothing whatsoever in for millions and millions of miles.

The spaces between individual stars, between individual galaxies, between individual clusters of galaxies and between superclusters of galaxies is mostly empty space. However, now and then we might come across a rogue planet, brown dwarf, or star which has been gravitationally wrenched from its galactic location by galactic collisions, near misses, or by the slingshot effect caused by orbiting too near a galactic black hole. Stars destined for such a fate can be recognized by their galactic escape velocity which will ultimately destine them to that fate.

.
 
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Thanks for all the posts which have been very helpful and just so mind boggling that I now wish to dig a hole and hide away from the unfathomable nature of the distances we are talking about...

"6 trillion miles" = a light year and there are millions of light years between galaxies - there's a lot of space out threre :(.
 
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"An object will stay remain at rest or continue at its constant velocity unless acted on by an external unbalanced net force", Newton's second law.



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  • #7
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Thanks for all the posts which have been very helpful and just so mind boggling that I now wish to dig a hole and hide away from the unfathomable nature of the distances we are talking about...

"6 trillion miles" = a light year and there are millions of light years between galaxies - there's a lot of space out threre :(.
Look up the Hubble Ultra Deep Field on wikipedia and youtube...it will blow your mind.
 

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