This image is my view of the top 20 grand design galaxies that I am able to image, which means above -40 degrees declination.  I have seen many slightly different definitions of a grand design spiral galaxy.  Typically, it is something like that defined in Wikipedia – “a spiral galaxy with prominent and well-defined spiral arms”.  These galaxies make up about 10% of the galaxies in the universe. 

The breakdown is as follows:
- 10% grand design spiral galaxies
- 60% multiple-arm galaxies
- 30% no well-defined arms at all

What makes a grand design spiral galaxy so grand?

At first, I was very impressed by the concept and view of grand design spiral galaxies.  But over time, I noticed that many of them just didn’t seem as “grand” as others.  And I came to the conclusion that they are 5 aspects which makes a grand design spiral galaxy “really grand”:

1.  The first aspect is a strong distinct arm structure.  What does this mean?  Many grand spirals have faint arms, or arms that are hidden a bit by arm fragments and offshoots.  The most impressive ones have arms which trace a clear path from the core out to the outer disk.

2.  The second aspect is arms which extend far around the core.  The best ones have arms which complete a full 540 degrees of revolution.

3.  The third aspect, and perhaps most underappreciated, is point symmetry.   A galaxy with perfect point symmetry will look exactly the same if you rotate your view 180 degrees.  My mouseover compares these 2 views for each galaxy to give you an idea of their point symmetry.  It is amazing to me that an object of such large mass, scale and complexity like a galaxy could have almost perfect point symmetry.  I believe that the order that symmetry provides in galaxies is appealing.

4.  The fourth aspect, and perhaps most obvious, is a face-on orientation to our view.  Such a view gives us the most dramatic and exciting glimpse of the galaxy structure.

5.  The fifth aspect, and most subjective, is spectacle.  This includes anything beyond the arm structure and orientation which enhances the beauty and wonder of the galaxy.  Examples include the presence of bright HII regions, dark dust lanes, central bars, or inner rings.

I ranked the grand spiral galaxies by a summed weighting of the 5 characteristics described above.  The poster shows the top 20 of these galaxies. 

Here is a list of them, starting with the highest ranked:
1.   M51
2.   Arp 1
3.   NGC 5364
4.   NGC 1365
5.   NGC 5371
6.   NGC 266
7.   NGC 6446
8.   NGC 4535
9.   M81
10. NGC 536
11. NGC 1300
12. M74
13. NGC 4314
14. NGC 210
15. NGC 4536
16. M95
17. M109
18. NGC 6118
19. NGC 1350
20. NGC 1530

And here some of the ones which just missed the cut:

NGC 3338
M101
NGC 3893
NGC 2903
M91
Arp 96

The links above will take you to my Astrobin image and description of each galaxy. They all reside in my Astrobin Grand Design Spiral Galaxies Collection.

I am sure that I missed a few nice grand spirals - please let me know below if you have a favorite that I have missed.

If you would like to access all my DSO compilation posters, please click here.