With the good fortune of clear weather, undergraduates stopped for a few moments in front of the Science Center yesterday afternoon to observe a partial eclipse of the sun.

A few students set up solar viewing equipment to get a better view of the eclipse, which lasted about an hour and a half. They had intended to watch the celestial phenomenon from the roof of the Science Center, but high winds made the equipment unstable.

In the Boston area, the moon covered 21.4 percent of the sun at 1:25 p.m, not enough for the unaided eye to notice, since the sun did not appear to be any darker.

A full eclipse of the sun was observed through parts of northern South America and the Caribbean.

Total eclipses occur every one-and-a-half to two years somewhere on Earth, said Daniel H. Phillips '99, who set up the viewing equipment for the event.

"It's really neat to see huge solar system bodies crossing each other," said Benjamin D. Oppenheimer '99, an astronomy enthusiast at the viewing.

According to Oppenheimer, the moon is 400 times smaller than the sun, but 400 times closer to the earth. As a result, the moon and sun appear to be the same size.

The next total eclipse will cross Europe and southwestern Asia on Aug. 11, 1999 and will be the last of the 20th century.

A number of Harvard astronomy professors were on the Caribbean island of Aruba to watch the event, according to professor of Astronomy Robert P. Kirshner.

Kirschner joined the crowd in front of the Science Center after teaching his Core class, Science A-35, "Matter in the Universe."

"It goes right into some primitive part of the brain," he said.

Kirschner also suggested that our long-standing fascination with eclipses persists largely because of their unusual nature and rarity, even though they are well understood and easily predictable with modern science.

"If you have ever been to a total eclipse, you would know it is the most frightening natural phenomenon," Kirshner said. "A partial eclipse--this is like kissing your sister."