M101 (NGC 5457) Pinwheel Galaxy

in Ursa Major is described by Burnham as "..one of the finest examples of a large face-on Sc type spiral and a beautiful object on  long-exposure photographs."   M101 was discovered by P. Mechain in 1781 and described in the same year by Messier as  "A nebula without star, very obscure and pretty large..." (Burnham).

M101 is at about 27 million light years distant and is approximately 170,000 light years in diameter.  It is classified as a peculiar spiral due to the displacement of the core from the center of the arms.

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Penryn, California
February/April 2003
FS-128 (ag, ST-4)
ST-10XME lrgb 15,20,20,20 minutes