How big is the Andromeda Galaxy?

[dwig]

Originally Posted by pdurrant

There are very few humans who have had a significantly different viewpoint.

In the real world that's true, but we're a bunch of fiction readers around here and many of the characters in the books we read do have significantly different viewpoints. Still, it would appear roughly the same size, given matching seeing*, from anywhere in the Milky Way. The distance from one side of the MW to the other is relatively small compared to the distance from the MW to Andromeda.

I all to often encounter annoying flaws in a fiction piece where the setting's rather different viewpoint, whether spacial or temporal, is not taken into account.

* "seeing" is a term that refers to the combined effect of various conditions that impact the ability to see astronomical objects. These include, but are not limited to, the air's clarity, turbulence, local light sources, ... .

[pdurrant]

Originally Posted by piperclassique

I thought it was a really long way to the chemist's

... but that's just peanuts to space!

[Bilbo1967]

Originally Posted by pdurrant

... but that's just peanuts to space!

You can buy peanuts at your chemist?

[piperclassique]

HHGG joke

[Dylrob]

I voted the blue one, cause I missed it. Also I don't like to guess.

Oh if only we could get rid of all this pesky light pollution so we could see the night sky as our ancestors did.

[pdurrant]

Originally Posted by Dylrob

Oh if only we could get rid of all this pesky light pollution so we could see the night sky as our ancestors did.

We could get rid of a lot of it, and save money, by getting the authorities to buy the right kind of street lighting. Most street lighting lets far too much light go above the horizon.

[wodin]

Originally Posted by pdurrant

We could get rid of a lot of it, and save money, by getting the authorities to buy the right kind of street lighting. Most street lighting lets far too much light go above the horizon.

Uhh... ? Don't you mean SPEND a lot of money? Where do you suppose those "authorities" get their money?

[piperclassique]

We could get rid of a lot of it, and save money, by getting the authorities to buy the right kind of street lighting. Most street lighting lets far too much light go above the horizon.

Even cheaper, tun them off after the pub closes.
In the village down the road from my unlit garden, lights go out at 22:00. Next house to me, straight line distance, 4km. Good for starwatching. On a good night I can see all of the pleiades naked eye (plus glasses, duh)
But it's still a long way to the chemist.

[wannabee]

Well I got that wrong. I know I've never seen it and guessed what it might be like. I guessed small oval. I have a free iOS app called Starmap Lite which positions it below the horizon tonight.
I typed in M31 and it draws a great big arrow in the star map so you can find the various heavenly bodies. You position the phone like a compass and it shows you the sky with all the names. It's really quite cool and everyone I've shown it to downloads it immediately.

[pdurrant]

Originally Posted by wodin

Uhh... ? Don't you mean SPEND a lot of money? Where do you suppose those "authorities" get their money?

No, I mean SAVE money. Street lights get replaced on a regular basis. If local authorities bought well-desgned street lights that didn't illuminate the sky, they would be more efficient, and cheaper to run. Also, they'd provide better, non-dazzling illumination.

I'm not suggesting that they switch them all over immediately, but that light pollution be taken into account when choosing replacements in the normal replacement cycle.

[Sweetpea]

Originally Posted by HomeInMyShoes

It would be super cool to see a galaxy in the night sky with the naked eye.

But you can see the Andromeda galaxy with the naked eye! If you can't, start lobbying against light pollution...

Spoiler:

naturally, you can't see it in al its splendor with the naked eye....

[Dylrob]

Originally Posted by pdurrant

We could get rid of a lot of it, and save money, by getting the authorities to buy the right kind of street lighting. Most street lighting lets far too much light go above the horizon.

Well I'm not familiar with the street lights on your side of the pond, but almost all of the ones in America are already the downward facing style:

[pdurrant]

Originally Posted by Dylrob

Well I'm not familiar with the street lights on your side of the pond, but almost all of the ones in America are already the downward facing style:

That sort of light is part of the problem. Yes, it faces down, but it also shines sideways and up. Note that the light emitting part shows below the supporting arm. This means that some of the light can go into the sky. It doesn't need to shine straight up to be a problem. Any light going above the horizon is the problem.

http://www.britastro.org/dark-skies/

[cromag]

Here in suburban New Jersey there's a very noticeable nighttime glow on the horizon in the direction of the New York City/Northern NJ Urban center. Even on a cloudless night there is enough dust and moisture in the atmosphere to catch and redirect stray light.