he taught for another 14 years at the University of Arizona. The first edition of his widely-used textbook appeared in 1916; the fifth edition appeared in 1955. His Lick Ph.D. thesis on the orbits of two cepheid variables was the first step toward the abandonment of the widely-held binary star theory of cepheid variation. During a 28-year association with the Mount Wilson Observatory he measured the expansion of the Crab Nebula (1921), discovered three variable stars in external galaxies (1922) and took a superb series of pictorial photographs of galaxies, nebulae and Milky Way fields. (M 12457) Name proposed by F. K. Edmondson.

Digital Camera and Digital Photography

Digital Camera and Digital Photography

Compared to film cameras, digital cameras are easy to use, fun and extremely versatile. Every day there’s more features being designed. Whether you have the cheapest model or a high end model, digital cameras can do an endless number of things. Let’s look at how to get the most out of your digital camera.

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