On the right, you see William Shatner, the actor who played Captain James T. Kirk on Star Trek. On the left you see the famous astronaut Chris Hadfield of the Royal Canadian Air Force. Col. Hadfield was recently commander of the International Space Station, where he gained fame as a science educator, musician, and mustache cultivator.
Col. Hadfield tweeted this photo and wrote, "Spent a day with 1 of my childhood TV heroes. Great delight - @WilliamShatner is a thoughtful & interesting man."