What happens during a solar eclipse? Experts explain the awe-inspiring phenomena to expect on April 8

Monday's total eclipse of the sun won't be just any old eclipse; it's being referred to as the Great American Eclipse, because it's going through some very populated areas of the United States. Solar eclipses actually occur every 18 months or so, but during most of them the spectacle is "wasted" on empty ocean. But tomorrow afternoon, the moon's shadow will leave 32 million Americans in 15 states briefly in the dark.