By Mike Wall 5/14/2012 1:37:21 PM ET Skywatchers in East Asia and the western United States should circle this upcoming Sunday on their calendars. That’s when a solar eclipse will block out most of the sun, leaving a spectacular “ring of fire” shining in the sky for observers located along the eclipse’s path. The event is what’s known as an annular solar eclipse — from the Latin “annulus,” meaning “little ring” — and its full