Buzz Aldrin, the second man to walk on the moon, will be a guest speaker at Serra High School in San Mateo today. Aldrin, who is traveling through the Bay Area to be a keynote speaker for an electronics convention this week, will address Serra’s student body at a school assembly. On July 20, 1969, Aldrin followed Neil Armstrong onto the moon’s surface. The assembly will be held from 10:55 to 11:55 a.m. “Aldrin is a significant historical figure in the United States,” Serra High principal Barry Thornton said.