SNAPSHOTS OF EARTH, taken from Saturn. “The Saturn photo op runs from 5:27 to 5:42 p.m. ET on Friday. That’s the time period when the light reflected by a toothy smile and a waving hand can make the 898.5 million-mile (1.446 billion-kilometer) journey from Earth to Saturnian orbit, in time to be captured by Cassini’s camera 80.4 minutes later.”