Can I Pick Some Brains??

[solarbreeze]

Greetings

I will soon introduce myself formally on the newcomers thread and there's honestly nothing to get too excited about with that.....lol

However, I have a burning question [or two] which I need to ask regarding constellations observable with the naked eye.

A general question is this.

Are all the stars which make up the most popular observable constellations and clusters..... situated within the Orion Arm? [Local Spur]

I realise that a star's individual mass, luminosity and distance all have a bearing on it's immediate visibility, but what I'm really trying to pin down are the general location of the stars that are readily viewable to the naked eye....even within light polluted areas.

For example, when I look at:

Cassiopeia, Ursa Major/Minor, Orion, The Pleiades, The Double Cluster, Andromeda, Perseus etc.....to name but a few....

....would it it be correct to say that I am merely observing stars situated within the Orion Arm?

Are there any readily visible [well known] stars which are situated within the Sagittarius Arm or the Perseus arm?

I guess I'm just trying to get a feel for 'distance' with this query.

If stars were all the same size and possessed an equal and consistent magnitude, then I suppose it would be much easier to draw a rough circle on a galaxy map indicating just how far one is capable of looking into space without the aid of magnification.

[Arguably, it would be pretty boring also...lol]

The muse for this question arose when, whilst on holiday....my brother in law once tried to point out Sirius to me many many years ago.

'Sirius' it soon transpired....was nought but a very static police helicopter monitoring the local 'hoodies' in some distant town.

Laugh we did....BUT....

....if ever there was an example of the perception deception involved in luminosity versus distance, this was it.

My brother in law still insisted he was stating the truth because he happened to know that the helicopter pilot's name was Sirius.

[There's some ready scouse humour for you]

Anyway, I digress.

To summarise...

The night sky with the naked eye?

Apart from Andromeda [M31] and a few other delightful deep field exceptions.... is it generally dominated by stellar bodies within the Orion Spur?

Any and all enlightenment greatly appreciated.

Mick

[Merlin66]

All the naked eye stars and globular clusters, nebulae etc are in our own Milky Way galaxy. The nearest stars are obviously in the Orion arm ( and others close by)

Looking towards Sagittarius you're seeing towards the core of the Milky Way.

Ken

[barkis]

The distance to some of the nearest stars can be measured using the earths orbit around the sun, which gives a baseline of

186,000,000 miles, using basic Trigonometry,, and the angular shift of a near star against a fixed one, distance can be established.

This is the only direct measurement, and stars over 400 light years need another method. A stars spectral colour is an aid to this, but you would need to look it up as to how. Or someone more knowledgable than me will describe it.

Ron.

[davew]

Hi Mick,

Download this little gem Where is M13? - Home

It should answer most of your questions in an easy to use graphical form.

If you want to know how it's worked out, go here for a very brief description The ABC's of Distances

Dave

[arad85]

The night sky with the naked eye?

Apart from Andromeda [M31] and a few other delightful deep field exceptions.... is it generally dominated by stellar bodies within the Orion Spur?

Generally, yes. There are some exceptions (Perseus double cluster for example).

The advice of downloading "Where is M13?" is a good one. It doesn't give star positions though, just the bigger objects. For the star distances, you may find this page useful: The Brightest Stars

BTW, M31, being a galaxy in its own right, isn't even in out own galaxy, let alone our own spur

[davew]

Hi,

M13 ? does show quite a few stars now. Go to Filters - tick stars - tick Bayer and Flamsteed. If you turn off all other filters and zoom in a touch 818 star positions show.

If you then go to Sky View and click on show all, when you click on a star it names it and shows its location in the Galaxy view.

I can't remember if the origional programme did this.

Dave

[arad85]

Oooh... Yes, it does... Ta. More for me to look at now

[solarbreeze]

Many thanks indeed for these responses...

Dave...

You've seriously put me right on the money with the:

Where Is M13... program.

I've downloaded it, followed your filter instructions...then zoomed in and obtained this as a screen-cap.

I'm going to have so much fun with this, I just know it.

Especially filtering out constellations and viewing them in 3D isolation.

That brief 'Escaping Plato's Cave' essay on the homepage wasn't wasted on me either.

I don't want to ramble on here, but I've always had a penchant for the evolution of mapping. I've pretty much exhausted this in terms of Earthbound geography and it has struck me that the assorted universe maps that are now appearing are the modern day equivalent of the ancient Earth maps.

With the benefit of knowledge and hindsight, somebody somewhere will one day look back at them with affection saying

" Awww....you can see them getting more and more detailed and accurate with each passing century...."

I've always thought that Earth centrated star maps are [understandably] subjective.

For example:

If you lived on a planet within the large Magellanic cloud and somebody landed their spacecraft and asked you if you knew the way to the Pleiades, you could hardly say:

" Yeah....it's in Taurus.....here let me draw you a map..."

Taurus is a subjective Earthly reference, and it's not really much use for the purpose of navigation from anywhere but on and around the Earth itself.

Anyway, cosmic mapping with A to B navigation in mind is not something we have to worry about too much at the moment.....lol

But migrating from 2d star maps to 3d is IMHO....definitely where it's going to be at in terms of getting a much better sense of that extra dimension.

Can you tell I take a rather dim view of astrology and it's rather wacky 'line of sight' inferences?

Lol....

Many thanks once again.

Mick

[Tim]

Can you tell I take a rather dim view of astrology and it's rather wacky 'line of sight' inferences?

Are you trying to imply that astrology is not proper science but a load of made up tosh? Good heavens! They'll be saying the earth isn't flat next!

That's a great looking tool pointed out there.

Interesting post, looking forward to more on this.

Welcome to SGL btw

TJ