Photo by Pittendreigh
M51 was discovered by Charles Messier in 1773. It is the first galaxy recognized as having a spiral character. Lord Rosse was the first to detect this nature in 1845, while using a 72 inch reflector. Until the 1920's, when Edwin Hubble conceived the galactic view of the universe, astronomers thought this was a solar system being created. M51 was listed as two different numbers in the NGC.
Here are three ways to find it.
Find Alpha Canum Venaticorum. Move your telescope north 9 degrees then east 5 degrees.
Or, find the star at the end of the Big Dipper (Alkaid), and move 3 degrees southwest.
Or, locate Alkaid and Mizar, the two end stars of the Big Dipper. Below the handle, find star 21. Alkaid, Mizar and 21 will form a triangle. Star 21 and Alkaid will form another triangle with M51.
WHAT TO LOOK FOR:
You should easily see a round glow with a distinctive nucleus. I find that it looks like a double nebula. On a good night, you ought to be able to see the spiral arms if you have an 8 inch telescope or better.