Why do many galaxies appear as spirals? A striking example is M101, whose relatively close distance of about 27 million light years allows it to be studied in some detail.
Click the figure below to see the interactive illustration of the The Pinwheel Galaxy (Messier M101 or NGC 5457).
The Pinwheel Galaxy (Messier M101 or NGC 5457), Golden Rectangles
Saturday, April 18, 2009