Comments on: In galactic collisions, might makes right

By: Sometimes a cigar galaxy is just a cigar galaxy | Bad Astronomy | Discover Magazine

Wed, 04 Jan 2012 12:48:47 +0000

[...] millions years ago as "recent", which astronomers do) collision with its neighbor M81, a gorgeous full-on spiral galaxy. The gravitational interaction sent gas clouds slamming into each other inside M82, collapsing them [...]

By: Neil Haggath

Neil Haggath — Sun, 16 Jan 2011 23:19:32 +0000

M81 is a very neat, symmetrical object, while M82 is a messier object!
Sorry, couldn’t resist it.

By: Mary

Mary — Sun, 16 Jan 2011 16:48:30 +0000

Thanks for the links, Messier Tidy Upper.
Mary

By: Messier Tidy Upper

Messier Tidy Upper — Sun, 16 Jan 2011 02:35:55 +0000

Tada! Found it finally :

http://blogs.discovermagazine.com/badastronomy/2010/05/17/obese-gluttonous-and-cannibalistic-is-no-way-to-go-through-life-son/

is the one I was thinking of!

By: Messier Tidy Upper

Messier Tidy Upper — Sun, 16 Jan 2011 02:25:57 +0000

@ ^ Mary : No worries, my pleasure.

By: Mary

Mary — Sat, 15 Jan 2011 18:54:08 +0000

Messier TidyUpper, thank you. I really appreciate your spending tbe time to provide an answer. I will search for that BA blog later today and have a look at the links you included.
The question came after my explaining that Andromeda and our Milky Way will eventually collide. Well, as you said, pass through each other is a better word than collide. I don’t think it was wrong comparing galactic activity in an expanding universe to varying weather patterns on Earth. Within the context of overall global warming, there are weather incidents that may, if looked at in isolation, seem to contradict global warming. However, conditions in different locations (closeness to large bodies of water, mountain ranges, etc.) influence localized weather. This is not surprising and is, in no way, a contraindication to worldwide global warming. In the same way, colliding galaxies in no way contradict the fact that overall the universe is expanding.
Thinking back, the anaolgy was okay, but I was not satisfied with a non astronomical explanation. I think I was a little brain fogged at the moment. Your information helps clarify things and I will get back to the questioner with a more specific/complete answer.
Your input is much appreciated.

By: Messier Tidy Upper

Messier Tidy Upper — Sat, 15 Jan 2011 13:25:48 +0000

Sorry but I can’t seem to find the BA blog post I’m sure I remember seeing which was titled something like “Something, something & gluttonous is no way to go through life son” (with the somethings replaced by betetr words obviously!) and featuring a particularly extreme example of a Central Compact Elliptical “cannibal” galaxy.

Tried a number of things – tags, search box options, etc .. with no success.

Afraid I’m stumped on this – can anyone else remember that one & help here, please? BA?

By: Messier Tidy Upper

Messier Tidy Upper — Sat, 15 Jan 2011 12:55:29 +0000

By: Messier Tidy Upper

Messier Tidy Upper — Sat, 15 Jan 2011 12:54:25 +0000

@ 16. Mary : While the cosmos as a whole is expanding, gravity still attracts and pulls nearby galaxies towards each other.

Galaxies are arranged in clusters and superclusters which are areas that contain more matter (the galaxies & perhaps – I’m not 100% sure – also more dark matter too)

Galaxies – like everything else are also moving rather than “staying still” and so when they come closer to each other, their mutual gravitational effects can pull them together leading to galactic collisions. In these collisions, the stars don’t (usually) collide but the galaxies pass through each other and then fall back towards each other and eventually merge. This will happen to our own Miliky Way and the Andromeda galaxy (M31) as the Bad Astronomer mentioned in his Death from the Sky book.

Hope that helps.

By: Mary

Mary — Sat, 15 Jan 2011 05:45:38 +0000

Perhaps someone can help me out here. I was trying to explain how, in our expanding universe where objects are moving apart, some galaxies are on a collision course. The question was thoughtful. I am not so happy with my answer. Help, please.

By: Messier Tidy Upper

Messier Tidy Upper — Sat, 15 Jan 2011 02:35:40 +0000

See :

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

For the wiki-basics on our Local group of galaxies.

Plus see :

http://wise.ssl.berkeley.edu/

For the WISE homepage – with a familiar image starring (or should that be galaxy-ing) there.

http://www.youtube.com/watch?v=6eZm3LHlyrs

for the Andromeda- Triangulum collision on Youtube.

By: Messier Tidy Upper

Messier Tidy Upper — Sat, 15 Jan 2011 02:35:13 +0000

@7. Kaptain K :

I won’t say it helps dominate the “local group”, but (although quite a bit smaller than the Milky Way and M31) M33 (in Triangulum) is a good sized ” grand design spiral” just a little bit farther away than M31.

I don’t know about “dominate” but I’m pretty sure that the Triangulum galaxy (M33) the next largest and next most important member of the Local Group after our Milky Way and the Andromeda Galaxy.

A past BA blog post lasty year noted the collision and interaction – continuing today (& more advanced than we see it across the gulfs of space) between the Triangulum and Andromeda galaxies.

By: Messier Tidy Upper

Messier Tidy Upper — Sat, 15 Jan 2011 02:25:40 +0000

Wiki-links here in case they’re handy / interesting for folks :

http://en.wikipedia.org/wiki/Messier_81

http://en.wikipedia.org/wiki/Messier_82

http://en.wikipedia.org/wiki/Messier_33

For more info on some the galaxies mentioned here.

By: Messier Tidy Upper

Messier Tidy Upper — Sat, 15 Jan 2011 02:25:18 +0000

Gloriusly splendid image – I love it.

@8. Chris A. :

@Barney Nichols (#1): “I wonder how big each galaxy would appear in the night sky for an inhabitant of those galaxies.”

M81 is about 92,000 l.y. wide. At 300,000 l.y. it would span an angle of about 17 degrees. So, size-wise, if it were that close to us it would fit nicely within the box formed by Orion’s shoulder and knee/foot stars (Betelgeuse, Bellatrix, Rigel and Saiph) (although not appearing in that part of our sky, obviously)! Wouldn’t that be a sight!

On another point: While M82 (the “Cigar” galaxy) _looks_ cigar-shaped, it is actually a spiral seen nearly edge on (tilted 80 degrees from face-on).

(ref.: Mayya, Y. D.; Carrasco, L.; Luna, A. (2005).“The Discovery of Spiral Arms in the Starburst Galaxy M82″. The Astrophysical Journal 628 (1): L33–L36.)

Thanks for that info. – neat to know. [Picturing it now.]

By: Sam H

Sam H — Sat, 15 Jan 2011 01:13:20 +0000

I just love the colour contrast !
I found a site 100 km south of my city of Calgary in the summer, and from there I could see the nebulae in Sagittarius with my naked eye. And with Sadie (my 8-inch dob), I saw M101, Andromeda, Triangulum, M13, the Ring Nebula, the Omega, Lagoon and Eagle nebulae, and several star clusters (only thing I couldn’t find was the Bubble nebula…). But most spectacular were the great curls of our galaxy, just stretched above. Visible as day…so big that a small creature such as me could only get only the faintest hints of it’s inconceivable vastness.

While the galaxy may not be crammed with alien civilizations as Carl Sagan believed, (probably only a few thousand of them out there at most), I hope that Gene Roddenberry was at least partially right about interstellar travel (google “Heim theory” and you’ll see what i mean).

By: Brian Too

Brian Too — Sat, 15 Jan 2011 00:30:19 +0000

Ah false colour images, why do you tease me so?

By: Dan Gerhards

Dan Gerhards — Fri, 14 Jan 2011 21:59:57 +0000

I’m one of those people who has seen M81 with the unaided eye. I was in Central Oregon in a vast swath of virtually-uninhabited desert on a high plateau. I was 30 at the time. So, yeah, really dark skies, and young eyes. I don’t think any of the group could see M82–probably because it is significantly smaller. (This was at the Oregon Star Party. Highly recommended.)

By: Chris A.

Chris A. — Fri, 14 Jan 2011 20:29:32 +0000

@Barney Nichols (#1):

“I wonder how big each galaxy would appear in the night sky for an inhabitant of those galaxies.”

M81 is about 92,000 l.y. wide. At 300,000 l.y. it would span an angle of about 17 degrees. So, size-wise, if it were that close to us it would fit nicely within the box formed by Orion’s shoulder and knee/foot stars (Betelgeuse, Bellatrix, Rigel and Saiph) (although not appearing in that part of our sky, obviously)! Wouldn’t that be a sight!

On another point: While M82 (the “Cigar” galaxy) _looks_ cigar-shaped, it is actually a spiral seen nearly edge on (tilted 80 degrees from face-on).

(ref.: Mayya, Y. D.; Carrasco, L.; Luna, A. (2005). “The Discovery of Spiral Arms in the Starburst Galaxy M82″. The Astrophysical Journal 628 (1): L33–L36.)

By: Kaptain K

Kaptain K — Fri, 14 Jan 2011 18:28:24 +0000

I won’t say it helps dominate the “local group”, but (although quite a bit smaller than the Milky Way and M31) M33 (in Triangulum) is a good sized ” grand design spiral” just a little bit farther away than M31.

FWIW: On a clear dark night, M31 was bright enough to catch my eye while I was driving, I pulled over into a rest area and, after my eyes adapted, I was just able to see M33.

By: Pete Jackson

Pete Jackson — Fri, 14 Jan 2011 18:23:43 +0000

“In a few hundred million years, when they pass again, I’m sure we’ll know more.”

If we can dodge all the bad things that can happen before then, many depicted on your Bad Universe TV documentaries!

In the WISE picture, a lot of structure from the high latitude dust cloud belonging to our Milky Way galaxy, but lying in the direction of M81, can be seen to the left and right of M81. See:

http://www.galaxyimages.com/UNP1.html

And many years ago, I remember how linear dust filaments would appear superimposed on the nuclear regions of M81 as seen in classic references like the “Hubble Atlas of Galaxies” (Sandage 1961).

By: Richard Drumm The Astronomy Bum

Richard Drumm The Astronomy Bum — Fri, 14 Jan 2011 17:20:41 +0000

I’ve always referred to M82 as the exploding cigar galaxy. Exploding with star formation works for me. No problem there! Never tried to see them with the unaided eye, though. Reeeeeally dark skies & young eyes might help…

By: Bill DeVoe

Bill DeVoe — Fri, 14 Jan 2011 17:18:06 +0000

@2 Dotan Cohen. I must have missed this reference because I’m not sure where you got the “three galaxies” thing. Phil only listed “our galaxy (the Milky Way) and Andromeda”. Makes sense if you make the Milky Way clause a sub-parenthetical (due to it already being in parentheses).

By: Sir Craig

Sir Craig — Fri, 14 Jan 2011 16:15:10 +0000

You may think M82 is a mess, but when I take a look at that composite you’ve presented it couldn’t look lovelier. I really need to figure out how to recreate these kinds of images using Photoshop actions…

By: Dotan Cohen

Dotan Cohen — Fri, 14 Jan 2011 15:40:18 +0000

> dominated by our galaxy, the Milky Way, and Andromeda
>

Three galaxies, huh?

By: Barney Nicholls

Barney Nicholls — Fri, 14 Jan 2011 14:12:36 +0000

I wonder how big each galaxy would appear in the night sky for an inhabitant of those galaxies.

if we can see andromeda with the naked eye and thats 2.5 million light years away how big would that appear if it was only 300000, i guess about 8 times larger