The MilkyWay from M31

[MalcolmP]

The view of the MilkyWay from Andromeda/M31

In another forum we were considering a wide field pic that a member had made of the MilkWay,
we identified a little fuzzy 'blob' in the right place for M31, extending a little to the right and left,
and I proposed that if there was an alien on a planet circling a star in M31 pointing a camera this way (wave !) we would be about - "here" - and I put a red dot about 2/3 or 3/4 of the way out from the centre on that fuzzy blob in that post.

But then I thort
(a) would we be seen edge-on like M31
(probably because M31 is seen close to the plane of the MilkyWay [ ?? ] )

(b) would we be seen to be to the left or to the right of the middle ? (?? I give up ! no idea!!)
We must be on one side or the other else if we were line of sight with the middle then M31 would be in Sagittarius ? would it ?

The camera was a regular terrestrial one, on a tripod doing a 30sec exposure, in the northern hemisphere (UK) so I dont think we have to do inverting and newtonian and multi whatsits things !

[geckzilla]

It wouldn't be edge on. I mean, our view of Andromeda isn't edge on, so maybe my definition of edge on more strict than yours. Sun would appear both on the right and the left side of Milky Way depending on the observer's orientation in Andromeda. Think north and south hemispheres on Earth. People in Australia and South America see the sky "upside-down" compared to what northern hemisphere observers are used to. This actually can cause a lot of confusion.

[Nitpicker]

When we look at the Andromeda Galaxy today, we are seeing what it looked like ~2.5 million years ago. As such, for your proposed alien observer from M31 to see us wave, it would need to exist ~2.5 million years in the future. Having said that, we may not have changed that much, as a galaxy, in so short a time. But I'm sure we'll look different in ~4 billion years, when the Milky Way and Andromeda galaxies are predicted to collide.

At the moment, the Andromeda Galaxy appears to us about 22 degrees "South" of our Galactic Plane. From this I deduce (possibly incorrectly, as my brain is starting to hurt) that we will appear to them (in ~2.5 million years) at an angle of about 22 degrees off "edge on".

[rstevenson]

But then I thort
(a) would we be seen edge-on like M31
(probably because M31 is seen close to the plane of the MilkyWay [ ?? ] )

There are various images of the whole sky in different wavelengths in which we can "see" where Andromeda is in relation to the plane of the Milky Way. (For instance, try this one from ESA.) Andromeda's a little off the plane, so observers there will see the Milky Way slightly tilted -- probably not tilted as much as Andromeda appears to us, but tilted nonetheless.

Rob

[geckzilla]

When we look at the Andromeda Galaxy today, we are seeing what it looked like ~2.5 million years ago. As such, for your proposed alien observer from M31 to see us wave, it would need to exist ~2.5 million years in the future. Having said that, we may not have changed that much, as a galaxy, in so short a time. But I'm sure we'll look different in ~4 billion years, when the Milky Way and Andromeda galaxies are predicted to collide.

At the moment, the Andromeda Galaxy appears to us about 22 degrees "South" of our Galactic Plane. From this I deduce (possibly incorrectly, as my brain is starting to hurt) that we will appear to them (in ~2.5 million years) at an angle of about 22 degrees off "edge on".

Now you are just putting way too much effort into this. At some point, someone at Asterisk mentioned that it's not good to get caught up on the whole light years thing and just take everything we are looking at as essentially now and I took that advice and never looked back.

[Nitpicker]

And from M31, the Sun would appear to the right of the centre of the Milky Way, assuming our Galactic North Pole was pointing upwards. In 2.5 million years, the Sun only completes about 1% of its orbit around our galactic centre.

[Nitpicker]

At some point, someone at Asterisk mentioned that it's not good to get caught up on the whole light years thing and just take everything we are looking at as essentially now and I took that advice and never looked back.

Although that was probably mentioned many moons ago, it is still pretty good advice. I was first introduced to the Special Theory of Relativity (that's the easy one) over twenty years ago, and at the speed of my mind, it's only just starting to sink in.

[geckzilla]

A fun little program anyone could use to help visualize a few things such as this as well as other things such as orbital paths through space and cool things like how our constellations look from places other than Earth is Universe Sandbox. I don't want to seem like I am endorsing a commercial product but I don't know of any free alternative. There is a trial version you can use for free, though. Attached is a screenshot I took from the program viewing Milky Way from the center of Andromeda (which is represented by a rather oversize, large star). Sun is circled and labeled.

Milky Way from Andromeda.

[Nitpicker]

A fun little program anyone could use to help visualize a few things such as this as well as other things such as orbital paths through space and cool things like how our constellations look from places other than Earth is Universe Sandbox.

Noice. Thanks geckzilla, I will check that out. I love the marketing on that page, especially the testimonial:

What took billions of years to create, I've destroyed in 5 seconds.

[geckzilla]

If you decide to buy it, it's only $10 on Steam. I have no idea why it's twice as much on their website. I got it on sale for a mere $3, if I recall correctly.

[Nitpicker]

Thanks, but I'm pretty sure that once any website detects I'm in Oz, the price roughly doubles. I've noticed entire industries build up to work around such price gouging, which often tends to propagate more price gouging. Cruel world. I shall destroy it with Universe Sandbox <evil laugh>.

[geckzilla]

Yeah, I think the big difference between software prices for the US and other places are due to various value added taxes. Most Americans have no idea what a VAT even is. Anyway, that doesn't change the fact that it's still going to be half as much via Steam.

[Nitpicker]

You may be right about Steam (until today, I thought it just the gaseous phase of water). However, it is often more than just tax. Several large multi-nationals have been caught out recently, failing spectacularly to justify their price variations from one part of the world to another. (Not that that makes them change their behaviour.)

[MalcolmP]

And from M31, the Sun would appear to the right of the centre of the Milky Way, assuming our Galactic North Pole was pointing upwards. In 2.5 million years, the Sun only completes about 1% of its orbit around our galactic centre.

Thanks Np.

And :
Thank you everyone, very interesting and thought provoking.
Whilst I was typing my question I was thinking someone will pick me up on how to tell an alien (by radio for example) which way is right and which left if you cant wave your arms about,
I think there was lots of talk (at the time of Frank Drake and the Arecibo Message) about sub atomic particle spin and parity and things, dont remember what the outcome was, but there I go Steaming away off subject
Nobody did, but I didnt expect to be picked up on sensu-stricto edge-on !!

"edge on like M31"

ok ok, "not face on like M33"
Oh now there's a question, if an alien in M33 was pointing a camera this way , , , oh never mind !!!
harharha

Ok, sorry, I should have said "tilted like M31"
I stand corrected about aliens who stand on their heads
(and I am desperately trying to avoid upsetting anyone in Oz with a tired old joke, ooops sorry Np )

[Nitpicker]

Whilst I was typing my question I was thinking someone will pick me up on how to tell an alien (by radio for example) which way is right and which left if you cant wave your arms about [...] Nobody did, but I didnt expect to be picked up on sensu-stricto edge-on !!

"edge on like M31"

[...]

I stand corrected about aliens who stand on their heads
(and I am desperately trying to avoid upsetting anyone in Oz with a tired old joke, ooops sorry Np )

Re left and right, I'm sure we can encode a message to the aliens with a link to Wikipedia, viz:
http://en.wikipedia.org/wiki/Relative_direction
(Or at least encode a map.)

Either way, I'd expect them to react with a "huh?"

...

I'd never considered "edge on" as a description for M31 before, so I suppose you confused me, which made me try to quantify our edge on'iness to it: ~22 deg.

...

I often bend over backwards to observe the Ecliptic, so as to see it the way most people do. (Better than lying down, due to poisonous snakes and spiders.) It is a pity to me, that this sort of thing seems more common, than the majority trying to see things from the perspective of the minority. Ho hum, back to the grind in my sub-tropical paradise on the backside of the Earth.

[MalcolmP]

I'd never considered "edge on" as a description for M31 before, so I suppose you confused me, which made me try to quantify its edge on'iness: ~22 deg.

oh dear, no problem, no not you,
I meant geckzilla's comment
"It wouldn't be edge on. I mean, our view of Andromeda isn't edge on, so maybe my definition of edge on more strict than yours"

a horrible misunderstanding crept in here, or there, !, probably due to my ineptitude in quoting stuff !!
His use of "strict" conjured up my vague memories (it was a long time ago) of Latin and biology of "sensu stricto"
Forgive me Np
...

"I often bend over backwards to observe the Ecliptic,"

What a picture that conjours up !
yes I know what you mean, I spent some time in Brazil and not only was it all upside-down but the clarity of the atmosphere and absence of light pollution meant that I was overwhelmed/disorientated with so many unaided-eye stars that celestial navigation was a bit of a problem !

My biggest mistake was to return to the UK but that's another story.

Ps. how does one Google this "Steam" thingy that Gz refed without getting tangled up with phases of water ??

back to the grind in my sub-tropical paradise on the backside of the Earth.

Grrrr, you poor ex-colonial thing, I've just taken delivery of 2&1/2ton of coal to stop my butt (is that an acceptable americanism?) freezing-off soon.

[Nitpicker]

how does one Google this "Steam" thingy that Gz refed without getting tangled up with phases of water ??

New to me too (you ex-imperial thing). I think this is what she (geckzilla) was talking about:

http://store.steampowered.com/app/72200/

[MalcolmP]

New to me too (you ex-imperial thing). I think this is what she (geckzilla) was talking about: http://store.steampowered.com/app/72200/

Thanks, £6.99 (GBP) wont break the bank !
---------------//-------------

she (geckzilla)

ooops ! how was I to know ? ! It would be impolite for me to ref all unknowns as "its" rather than hes or shes
>> stage left >>>
----------------//--------------
Oh whilst I we are amusingly going offtopic
"(you ex-imperial thing)"
lol! touché brill !
I think I remember from long ago that america was a colony, canada was a dominion but
ummm errr sorry, what was Oz, I think I might have been in error saying ex-colony ? sorry (except being bothered by an absentee monarch ? heheee (gladly post them to you, free of charge) )
backstory :
My ancestors were border rievers so I dont know if they were hung for stealing cows from the english or sheep from the scots
(/offtopic, apologies to anyone not finding this amusing, honest!)

[Nitpicker]

Terra Australis was home to a few British colonies, the first being New South Wales in 1788. But we Nitpickers came to The Commonwealth of Australia a decade or so after the federation of the colonies in 1901. This never stopped my grandfather from claiming we came from a long line of Scottish sheep stealers, however, so perhaps it was by chance that we did not come sooner.

No need to send us your monarch (and ours) -- we have a vice-regal ring-in down here, and she throws a ripper morning-tea. Still, our Governor-General is a pity, because I really quite like the idea of outsourcing our head-of-state. Not to mention that monarchy is my favourite form of ridiculous government.

[geckzilla]

ooops ! how was I to know ? ! It would be impolite for me to ref all unknowns as "its" rather than hes or shes
>> stage left >>>

No worries. It is, at best, an ambiguous name if you think about it but to western eyes it seems masculine. Gojira was never assigned a gender in the original films. If it laid eggs, though, it would have certainly been female.

[MalcolmP]

Oh yes, commonwealth, that rings a bell,
never knew what it meant,
nor for that matter what a dominion etc was !

but hang on, wasnt one (or a few?) American thingies commonwealths?
Massachusetts eg ?

"Not to mention that monarchy is my favourite form of ridiculous government."

Quite so !

"No need to send us [your our their] monarch"

Oh shame, I've been trying to get rid of them for years now
you shure you dont want 'em ?

"if you think about it"
"Gojira was never assigned a gender"

Who ?

"This never stopped my grandfather from claiming we came from a long line of Scottish sheep stealers"

Sheep stealers eh ? So,,, we might be related !
I recently discovered that I have a 3rd cousin in Oz. never before mentioned in family histories !!

How did we get here via M31 ???????? !!

g'night,,

[Nitpicker]

Not quite. See: http://en.wikipedia.org/wiki/Federation_of_Australia

The Federation of Australia was the process by which the six separate British self-governing colonies of Queensland, New South Wales, Victoria, Tasmania, South Australia, and Western Australia formed one nation. They kept the systems of government that they had developed as separate colonies but also would have a federal government that was responsible for matters concerning the whole nation. When the Constitution of Australia came into force, on 1 January 1901, the colonies collectively became states of the Commonwealth of Australia.

The efforts to bring about federation in the mid-19th century were dogged by the lack of popular support for the movement. A number of conventions were held during the 1890s to develop a constitution for the Commonwealth. Sir Henry Parkes, Premier of New South Wales, was instrumental in this process. Fiji and New Zealand were originally part of this process, but they decided not to join the federation.

And yes, we might be related. Quite a small island you've got there.

[Nitpicker]

Sir Henry Parkes, Premier of New South Wales

To segue back to astronomy, a town in NSW was named after Sir Henry, and later, the Parkes Observatory was built nearby:

Click to view full size image

http://en.wikipedia.org/wiki/Parkes_Observatory

[MalcolmP]

Not quite..

Not quite what, you lost me there, that amber nectar must be getting stronger

Quite a small island you've got there.

For heavens sake what are you on ?
Quite a big ecological disaster continent you have there

Yes I knew about the Parkes telescope, thank you

goodby

[Nitpicker]

Not quite..

Not quite what, you lost me there, that amber nectar must be getting stronger

Quite a small island you've got there.

For heavens sake what are you on ?
Quite a big ecological disaster continent you have there

Yes I knew about the Parkes telescope, thank you

goodby

To explain:

You originally asked whether Oz is an ex-colony.
I replied it was once several colonies, but is now a commonwealth of federated states (where commonwealth is a term meaning a political community, different from the Commonwealth of Nations).
You replied "Oh yes, commonwealth, that rings a bell".
This implied to me that you think a colony, or an ex-colony, might be the same thing as a commonwealth, or the Commonwealth. It is not (quite), so I replied in more detail.
You got upset, so now I'm explaining. (Related? It sounds like we're married!)

Australia has a greater land area than the United Kingdom, certainly true. You and I might be related, strangely true. Humans (many of them British) have adversely affected parts of Australia's ecology, sadly true. I wish you well Malcolm -- you enjoy that 2.5 tons of coal over the winter. And you might be able to plug into a nuclear power plant, too. Plenty of coal and uranium here, mate. We're here to help!

I mentioned the Parkes Observatory to bring this forum topic smoothly back to astronomy. And back we are again ... ah, that's better!