Just how big are those Deep Sky Objects?

I assembled a collection of common DSO's that I have shot and created a collage in which all objects are at the exact same scale to each other as seen from Earth. This gives you a clear picture of how small and how large some objects are in the sky. I tossed in the moon as a comparison. Yes - M31 is really that big - and M57 is that small (if you even find it)!

You may use this image freely. Educators please email me if you want a high-resolution copy for printing.

The collage includes (left to right - top to bottom):

M42/43 (Orion nebula)
M101 (Galaxy in Ursa Major)
NGC 2024 (Flame Nebula)
Barnard 33 (Horsehead Nebula)
M20 (Trifed Nebula)
M45 (Pleiades Star Cluster)
M33 (Galaxy in Triangulum)
M17 (Omega/Swan Nebula)
M1 (Crab Nebula)
Luna
M57 (Ring Nebula)
M51 (Whirlpool Galaxy)
NGC 7635 (Bubble Nebula)
NGC 6207 (Galaxy in Hercules)
M13 (Globular Cluster in Hercules)
NGC 884 & NGC 869 (Double Cluster)
NGC 6888 (Crescent Nebula)
M27 (Dumbell Nebula)
M8 (Lagoon Nebula)
NGC 7293 (Helix Nebula)
M31 (Andromeda Galaxy)
M32 (Galaxy near Andromeda)

These are all single film exposures using Kodak Elite Chrome 200 and Fujichrome 400F Provia. The scope was a Meade LXD75 8" Schmidt Newtonian and manual guiding was accomplished with an Orion 910mm f/l guidescope. Exposures ran from 20 minutes (M51) to 45 minutes (M31) - except the moon, which was much less!

Clear skies to you!

Peter Kennett
www.PetesAstrophotography.com

Attached Image:

Peter,

A nice piece of work and really shows the relative sizes of these objects. I don't think I've ever seen a collage quite like it. Nice job!

dan

Peter

It's always nice when someone gives us a new perspective on things. Thanks for the effort, it is well appreciated.

JUD

Peter,

Your collage is very striking indeed. However, I believe that M31 has been measured to be some 5 degrees, or 10 lunar diameters, in extent, which is much larger than indicated. Its apparent size is typically 6 lunar diameters or more.

"Under "normal" viewing conditions, the apparent size of the visible Andromeda Galaxy is about 3 x 1 degrees (our acurate value, given above, is 178x63 arc minutes, while NED gives 190x60'). Careful estimates of its angular diameter, performed with 2-inch binoculars, by the French astronomer Robert Jonckhere in 1952-1953, revealed an extension of 5.2 times 1.1 degrees (reported by Mallas), corresponding to a disk diameter of over 250,000 light years at its distance of 2.9 million light years, so that this galaxy is more than double as large as our own Milky Way galaxy!"

http://www.seds.org/messier/m/m031.html

Dave Mitsky

Beautiful. Thanks for posting it Peter.

Peter,

Thanks for a most useful piece of work! I hope you don't mind if I include this image in with a talk I am giving later this year to my local Astronomical Society on "Astronomical Scale". Is there any chance that you have a higher res image available that could be emailed?

Nice Job, set it as Desktop for the month, I change them every month and your image is the choice for the next month.

Nice I've always wanted to see this done. I like comparisons like this. Thanks!

With the moon, you can compare it with the size of Earth bound objects - I took Alan Friedmans picture of crater Pitatus the other day and overlaid it with a picture of South Florida (and the Florida keys) scaled to size. Pretty startling to see how big Florida would look if we sent Alan to the moon with his telescope.