document: Solar telescopes yielded views of flare-producing sunspots and silhouetted mountains on the moon Tuesday as crowds gathered to watch a partial solar eclipse visible across western North America . `` There was a childlike delight with the wonder of nature , '' said Ed Krupp , director of Griffith Observatory in Los Angeles , where 600 children and at least 400 other people watched the moon block out 37 percent of the sun 's surface at 10:50 a.m. PST . `` It was certainly a lively crowd , '' he said . `` There was a festival atmosphere . '' `` It 's kind of neat , '' said map maker Jan Mayne , who was among dozens of people watching the eclipse through two types of solar telescopes at the California Institute of Technology in Pasadena . As the moon passed between the Earth and sun to cause the partial eclipse , those watching through Caltech 's telescopes could see mountains on the edge of the moon silhouetted against the sun . Also visible were gas jets on the sun 's surface and a giant group of sunspots that on Monday produced the most intense solar flare _ a burst of heat and radiation _ since 1984 . `` There was a stunning view of that large sunspot group , '' Krupp said . The eclipse was visible to at least some extent west of a diagonal line stretching roughly from Mazatlan , Mexico , northeast to Dallas and Chicago . Views were best farther west and north . But because the eclipse was partial most people did n't notice the slight dimming of sunlight . `` You ca n't tell the difference between a partial eclipse and a second-stage smog alert , '' joked one observer at Caltech . Several people viewed the eclipse through welder 's helmets in downtown Anchorage , Alaska , where the moon obscured 80 percent of the sun at 9:13 a.m. AST . In San Francisco , the moon eclipsed 46 percent of the sun at 9:52 a.m. , but the event was n't visible because of clouds that were so thick they delayed arriving flights at the airport . A slight dimming was noticed in Seattle , where partly cloudy skies allowed a glimpse of the 56 percent eclipse at 10:10 a.m. PST . The percentage of the sun blocked out and time of maximum eclipse at other locations included 52 percent at 11:28 a.m. MST in Edmonton , Alberta ; 46 percent at 11:09 a.m. MST in Boise , Idaho ; 36 percent at 11:10 a.m. MST in Salt Lake City ; 35 percent at 9:58 a.m. PST in Las Vegas ; 25 percent at 11:17 a.m. MST in Denver ; 15 percent at 12:42 p.m. CST in Minneapolis , and a measly 3 percent at 12:44 p.m. CST in Milwaukee . Fearful that people would suffer eye damage during the eclipse , scientists warned against staring at the sun directly or through inadequate filters , including smoked glass and photographic film or filters . Alan MacRobert , spokesman for Sky & Telescope magazine , said there were 245 known eye injuries in the United States after an eclipse in 1970 , but warnings about the danger reduced the number to three during a 1984 partial eclipse . From any single spot on Earth , a partial eclipse occurs every several years , said Ken Libbrecht , as assistant professor of astrophysics at Caltech . Total solar eclipses are visible from any single location roughly once every four centuries , though they are visible about every two years from somewhere on Earth , he said . The next total eclipse will happen July 11 , 1991 , sweeping across Hawaii , the Pacific Ocean , lower Baja California in Mexico , the west coast of Central America and finally Colombia and Brazil , MacRobert said .
extractive_keyphrases: solar telescopes partial solar solar eclipses eye injuries eye damage north america stunning view