Where are all the stars and stuff...?

[PhotoGav]

No, it's not another 'this damn weather is getting me down, where are all the stars and stuff?' thread - though it's tempting...

My question concerns trying to get my head around how far various things are away from us. I am beginning to organise the night sky as follows: nebulae are all 'cloud' systems in our own Galaxy, the Milky Way, so not that far away from us. Galaxies are obviously outside our own Galaxy at a whole range of distant distances from us.

So, first up, is that necessarily true? Are some nebulae that we see beyond our Galaxy? Surely they must be, but then maybe not?

Now on to stars - where are they? Are the stars that we see all relatively close really? How do they compare to M31, The Andromeda Galaxy - our nearest neighbour? How far can the naked eye see? Once you start looking through a telescope, I presume that fainter stars come into view that are further away? How about clusters, the visible ones like M45, The Pleiades or M13, The Great Hercules Cluster - where are they?

As you can see, I don't have that much idea and I haven't trawled the net for answers yet, hoping that you good folk of SGL will put me on the right track here!

[Knight of Clear Skies]

The night sky is a great jumble of time. Most stars visible to the naked eye are relatively close, within one or two hundred lights years, but some are much further away. Deneb in Cygnus for example is estimated to be 2,600 light years away, being perhaps 100,000 times brighter than our Sun. Globular clusters are mostly located in the galactic halo and are further away, the closest two are about 7,200 light years away. The Andromeda galaxy is about 2.5 million light years away, but given its size looking from one edge to the other is going back in time another 200,000 years. Triangulum is about 3 million light years away.

The extra-galactic nebula with the largest apparent size is the Tarantula Nebula in the LMC, which is bigger than the Moon even at a distance of 160,000 light years.

[PhotoGav]

Mmm, interesting, thank you. I wasn't far off with my thoughts then!

[Steve Ward]

Pretty sure that all the stars you can see naked eye , around 2,500 , are situated in the Milky Way our own galaxy.

[JimFR]

Theoretically, given perfect seeing and an extremely bright object, the only limit to naked eye seeing distance is as far back as the optically opaque phase of the universe's evolution... about 200000 years after the Big Bang.

[Knight of Clear Skies]

I found this article with a map of the Milky Way helped me visualize things a little better. Our view is very restricted by the dust in the arms but we can see all the way to the core in the direction of Sagittarius, as the central bulge extends above and below the disc. I also like this 360 degree panoramic view by Axel Mellinger, available in a pannable and zoomable browser.

Hope that's some help, as a race we haven't got around to signposting the universe adequately but I hear it welcomes careful drivers.

[Stu]

You are basically correct in what you are assuming.

Any of the naked eye stars are within our galaxy, and relatively close. All the major nebulae and clusters are also within the Galaxy, and more than that they are on our side of the galactic centre because the dust and cloud in the centre obscures anything behind it. The Milky Way is the diffuse light of millions of stars forming the spiral arms of our galaxy.

Globular clusters orbit in a halo around our galaxy.

Galaxies such as M31, M33, the large and small Magellanic Clouds all form part of the local group of gravitationally bound galaxies.

You can see nebulae and globular clusters in other galaxies. NGC604 is one I've recently observed in M33, and G1 is a globular cluster orbiting M31 which is visible in large scopes.

Some of the chaps on here have observed Quasars which are extremely distant, very bright (in an absolute sense) objects which can be identified. These are probably the most distant observable objects in the universe.

You will now hear a sort of squidgy thump as I reach the edge of my cliff of ignorance, and fall off [emoji6][emoji6]

[Size9Hex]

I think you're asking a great question, and it's one I'm slowing answering for myself as I look round the sky. Here are two maps of the universe on a logarithmic scale that should help:

http://www.astro.princeton.edu/universe/all100.gif

https://xkcd.com/482/

[ronin]

Basically everything you can see is inside our galaxy except as you say the other galaxies - to an extent it may depend on what is defined as a galaxy.

We cannot see individually a star in another galaxy, to far and too many to make out individual ones and nebula are again too far and too faint to make them out. I am not including stars that go nova, and even those are not really seen as an individual star.

Orbiting our Milky Way there are a number of orbiting dwarf galaxies, I presume that some of these are visible if in the right part of the world, good skies and good equipment. This is where the "what is defined as a galaxy" comes into it. It means is a dwarf galaxy considered as "in" the Milky Way or not.

You might want to consider the "distances" as In, Around or External to the Milky Way.

[Stu]

Basically everything you can see is inside our galaxy except as you say the other galaxies - to an extent it may depend on what is defined as a galaxy.

We cannot see individually a star in another galaxy, to far and too many to make out individual ones and nebula are again too far and too faint to make them out. I am not including stars that go nova, and even those are not really seen as an individual star.

Orbiting our Milky Way there are a number of orbiting dwarf galaxies, I presume that some of these are visible if in the right part of the world, good skies and good equipment. This is where the "what is defined as a galaxy" comes into it. It means is a dwarf galaxy considered as "in" the Milky Way or not.

You might want to consider the "distances" as In, Around or External to the Milky Way.

If you are talking about naked eye observing then that's correct, but we've already discussed that nebulae and globular clusters can be observed telescopically in other galaxies.

The LMC and SMC are dwarf galaxies which are visible to the naked eye in the Southern Hemisphere so you don't need good equipment. They are separate entities which are gravitationally bound to our galaxy.

The Tarantula nebula is visible in the LMC. I'm not sure however whether any individual stars are observable with a scope, it would not surprise me if they are.

[Scott]

Pretty much what Stu has said although, If I were a pedant (which I am ) the nearest of the objects you mentioned is the milky way...you're standing on it

As for the stars, this will show just how little we can see

[estwing]

where did you get that pic from Scott?...that great work with your own equipment!?

[Scott]

where did you get that pic from Scott?...that great work with your own equipment!?

Yes mate, I imaged (or is that imagined) the milkyway last time I went to Andromeda Galaxy, or mdchvkslaaj as they prefer to call it

[estwing]

I know you have travelled...but that's just showing off!

[Mr Spock]

Andromeda eh. I always knew you weren't from around here...

[deadmeat30]

Well just goes to show you that no matter how big the expanse is that we can see, its still nothing as too whats out there...

[nameunknown]

where did you get that pic from Scott?...that great work with your own equipment!?

was tempted to say the same (perhaps he has a very long garden)  - but looking through the scope I can't see the "yellow circle" - so this is obviously a plot by the Zygons...

[Scott]

was tempted to say the same (perhaps he has a very long garden)  - but looking through the scope I can't see the "yellow circle" - so this is obviously a plot by the Zygons...

I believe the yellow circle requires a 22" scope

Sorry Gav, I'll stop being a clown now

[JonC]

A quick comment from me. I have a basic understanding of astronomy, mainly based around a few books, the sky at night, and other TV stuff. I recently joined a local astronomy club and have been blown away with the quality of talks done by both other members and invited speakers. I have also visited talks at another club, and again the lectures have been incredibly interesting and professional.  Obviously it will vary club to club, but do keep an eye open for whats on offer at clubs. 

[Stub Mandrel]

Pretty much what Stu has said although, If I were a pedant (which I am ) the nearest of the objects you mentioned is the milky way...you're standing on it

As for the stars, this will show just how little we can see

You can cause a lot of trouble with things like that

Is that a fairy cake? >MUNCH<

[Stub Mandrel]

More seriously, I've managed to image some globular clusters in M32, mag around 14.5 so they should be visible in quite modest scopes, although indistinguishable from stars.

Through a scope you should be able to see some quasars (I must look some time) which are orders of magnitude further away than most galaxies.

[PhotoGav]

Fascinating reading, thank you for your input everyone (even the silly stuff, that made me smile!). Great pics auspom & Paul - puts it all into a great deal of perspective. I never realised how very 'close' the majority of what we look at / image really is, and it's bleedin' miles away!

The more I get into all of this, the more fascinating it becomes. Good reminder about the club 'lectures' JonC - I am a member of a very local club and have attended a couple of sessions that have been most informative. I will indeed look slightly further afield for other events.

It's just a shame we can't actually see any of it at the moment........!

[Jimtom]

We can only see 0.000003% of the 200-400 billion stars that inhabit the Milky Way with the naked eye!

Douglas Adams was right, Space IS big  

[niallk]

Here's a pretty interesting little programme: it plots out the messiers relative to the sun in the milkyway. I got it first on the coverdisk of 'Sky at Night'

http://www.thinkastronomy.com/M13/

[Jimtom]

Here's a pretty interesting little programme: it plots out the messiers relative to the sun in the milkyway. I got it first on the coverdisk of 'Sky at Night'

http://www.thinkastronomy.com/M13/

Thanks for the link. An interesting program and fun to play with. I've just missed the end of Downton :)