A total solar eclipse occurs about every 18 months somewhere in the world, but very few are in as convenient a location for viewing as the eclipse that will occur on August 21.  Troy Carpenter of the Goldendale Observatory says many eclipses occur over an ocean or areas of very little population.  But this one offers many viewing opportunities, going across the North American continent, starting in the Pacific Ocean, crossing north-central Oregon, going through the country, and exits in South Carolina, all in about 93 minutes.  The last one to cross the nation from west to east was in 1919, even though there have been several eclipses that could be observed in parts of the country.  Carpenter reminds people if they are going to look directly at the eclipse, they must wear certified filtration glasses.