The "Pin Wheel Galaxy" or M101 was discovered by Pierre Méchain on Tuesday, March 27, 1781 in the constellation Ursa Major. Pierre, like his colleague Charles Messier, enjoyed searching and observing comets and kept coming across lots of other nebulous objects. They corresponded frequently to keep a list of them.
Messier 101 is rather large extended object covering a span of 22 arc minutes. Only the central core is visible in small scopes under light polluted skies.
To really appreciate this grand spiral you need to get away from city lights and observe it with 16 inch of aperture or more. Put on a UHC filter and you might see 3 and probably more bright blotches. These clouds of glowing gas and plasma are composed of ionized atomic hydrogen or H-II. Hot, blue stars are being formed in these clouds. The stars emit ultraviolet light which ionizes the hydrogen gas. Around 3000 of these regions have been imaged in M101.
Messier 101 is approximately 52,120 parsecs or 170,000 light years across and contains perhaps 1 trillion suns. It is located 8.37 million parsecs or 27 million light years from our solar system.
Image Credit: Brian Kimball, Longmont Astronomical Society