M51 vs. M82

From by light polluted backyard, I cannot
find M81 and M82 with binoculars, but I can make
them with my 4.5" reflector. However, M51
keeps eluding me, even though it is listed as having
the same magnitude and about the same size as M82.
Is M51 a notoriously more difficult object than M82?

Thanks,
Eric

Hi Eric,

Here is a screen shot from Desktop Universe. It shows a few more stars than you will see, but if you stick with the brighter ones, it should be close. The program shows the last star in the big dipper handle, and I have added the star hop lines to M51. The size of M51 is exact as it's a CCD image, but the brightness could vary a lot depending on your seeing conditions.

Hope this helps !

David Simons

Attached Image:

Galaxy sizes can be misleading if only the long axis size is quoted. The SEDS Messier website lists M82 as 9x4 arc-minutes and M51 as 11x7, both at magnitude 8.4. So for the cigar-shaped M82, the total area is about half that of the rounder-shaped M51. Thus more surface brightness for M82.

All of these galaxies were challenging for me when I was a beginner. A darker sky makes a big difference for galaxies.

Mike