The transit of Venus is a rare event, and this afternoon will likely be your last chance to experience it???the next one will not happen until 2117.From Pasadena, Venus will begin creeping across the sun at 3:06 p.m., and the transit will be visible until the sun sets at 8:02 p.m.Caltech's Astronomy Outreach group will host a viewing event from 3:00 p.m. to 7:30 p.m. at the Cahill Center for Astronom