UT: How Big Are Galaxies?

[bystander]

How Big Are Galaxies?
Universe Today | Jason Major | 2013 Apr 03

Galaxy size comparison chart

Galaxy sizes including IC 1101, the largest-known galaxy.

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(Image Credits: Rhys Taylor)

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I’m going to refrain from the initial response that comes to mind… actually, no I won’t — they’re really, really, really big!!!! </Kermit arms>

Ok, now that that’s out of the way check out this graphic by Arecibo astrophysicist Rhys Taylor, which neatly illustrates the relative sizes of 25 selected galaxies using images made from NASA and ESA observation missions… including a rendering of our own surprisingly mundane Milky Way at the center for comparison.

(Warning: this chart may adversely affect any feelings of bigness you may have once held dear.)

According to Taylor on his personal blog, Physicists of the Caribbean (because he works at the Arecibo Observatory in Puerto Rico) “Type in ‘asteroid sizes’ into Google and you’ll quickly find a bunch of images comparing various asteroids, putting them all next to each at the same scale. The same goes for planets and stars. Yet the results for galaxies are useless. Not only do you not get any size comparisons, but scroll down even just a page and you get images of smartphones, for crying out loud.”

So to remedy that marked dearth of galactic comparisons, Taylor made his own. Which, if you share my personal aesthetics, you’ll agree is quite nicely done.

“I tried to get a nice selection of well-known, interesting objects,” Taylor explains. “I was also a little limited in that I needed high-resolution images which completely mapped the full extent of each object… still, I think the final selection has a decent mix, and I reckon it was a productive use of a Saturday.”

And even with the dramatic comparisons above, Taylor wasn’t able to accurately portray to scale one of the biggest — if not the biggest — galaxies in the observable universe: IC 1101. For an idea of how we measure up to that behemoth, he made this graphic: (zoomable version here)

That big bright blur in the center? That’s IC 1101, the largest known galaxy — in this instance created by scaling up an image of M87, another supersized elliptical galaxy that just happens to be considerably closer to our own (and thus has had clearer images taken of it.) But the size is right — IC 1101 gargantuan. At an estimated 5.5 billion light-years wide, over 50 Milky Ways could fit across it!

And considering it takes our Solar System about 225 million years to complete a single revolution around the Milky Way… well… yeah. Galaxies are big. Really, really, really, really big!

</Kermit arms>

Now if you’ll pardon me, I need to go stop my head from spinning…

Read this and more on Rhys Taylor’s blog here, and add Rhys to your awesome astronomy Google+ circles here. And you can find out more about IC 1101 in the video below from Tony Darnell, aka DeepAstronomy:

Click to play embedded YouTube video.

Infographic : Galaxy Size Comparison Chart
Physicists of the Caribbean | Rhys Taylor | 2013 Apr 02

[Ann]

I love the Galaxy Size Comparison Chart, but I find the text on the chart very hard to read. For example, there is a picture of a pair of merging galaxies at center left, just to the right of the radio galaxy with the huge pink radio lobes. I tried to see what the merging pair is called, and I thought it said "NGC 5670". so I looked up NGC 5670 with my software. It turned out to be a modest-looking S0 galaxy. The designation of the merging pair is NGC 6670, but it didn't look that way to me.

Is there a way to enlarge the chart a bit more, so that the caption gets easier to read?

Ann

[ErnieM]

I love the Galaxy Size Comparison Chart, but I find the text on the chart very hard to read. For example, there is a picture of a pair of merging galaxies at center left, just to the right of the radio galaxy with the huge pink radio lobes. I tried to see what the merging pair is called, and I thought it said "NGC 5670". so I looked up NGC 5670 with my software. It turned out to be a modest-looking S0 galaxy. The designation of the merging pair is NGC 6670, but it didn't look that way to me.

Is there a way to enlarge the chart a bit more, so that the caption gets easier to read?

Ann

The original post has a zoomable version http://zoom.it/qbvd I toggled to the full page screen and put the cursor over the galaxy of interest then click to zoom in.

[Ann]

Thanks, ErnieM! Unfortunately, the zoomable chart is the one I found the least interesting. The other one isn't zoomable, as far as I can understand.

Ann

[rstevenson]

And the zoomable one allows zooming in past its native resolution, so that the individual galaxies and their associated text are visibly pixellated. It's a great idea to present the size comparisons this way, but a full resolution version of each image would be a big improvement. (Maybe the author is waiting for offers from publishers.)

Rob

[Beyond]

I love the Galaxy Size Comparison Chart, but I find the text on the chart very hard to read. For example, there is a picture of a pair of merging galaxies at center left, just to the right of the radio galaxy with the huge pink radio lobes. I tried to see what the merging pair is called, and I thought it said "NGC 5670". so I looked up NGC 5670 with my software. It turned out to be a modest-looking S0 galaxy. The designation of the merging pair is NGC 6670, but it didn't look that way to me.

Is there a way to enlarge the chart a bit more, so that the caption gets easier to read?

Ann

Ann, i set my screen magnification to 400% and could read the chart just fine. Just bring up the chart on the screen... click tools, that little gear looking thingie under the red rectangle, put the cursor on zoom-but don't click! To the left a zoom chart should appear. Slide the cursor over and click the magnification you want, and BINGO! instant bigger. Mine goes up to 400%. You'll then have to use the scroll bars to navigate up-down and left-right. When you're through, just reduce the magnification to the level you want. I normally run 125% for everything.
Hope that helps.

[Rhysy]

For the record, the author is quite flattered by the attention this is getting, but isn't waiting for offers from publishers. Of course he'd have to discuss such matters with his employers, were it to happen (also, print-size versions are actually non-trivial to render because the image size requires a ton of memory, and likely some of the galaxy images will need tweaking). However the author also despises text which is too small to read with the firery passion of a thousand flaming suns, so now both images are zoomable (they're both now linked via my website and blog) :
http://zoom.it/ptPq
http://zoom.it/qbvd

[rstevenson]

For the record, the author is quite flattered by the attention this is getting, but isn't waiting for offers from publishers. ... the author also despises text which is too small to read with the firery passion of a thousand flaming suns, so now both images are zoomable ... .

Thanks Rhys for your excellent work.

Rob

[Ann]

Yes, Rhys, thanks a lot!

Ann

[Rhysy]

The zoomable versions have changed because there was an error in the size of a light year. It isn't 9 billion kilometers (which would be smaller than the solar system !!! ) it's 9 trillion. I guess removing the offending images breaks zoomit, so here are the new links.

http://zoom.it/zQuq
http://zoom.it/dsLl
http://zoom.it/a1fo
http://zoom.it/kgES