It's Bob Newhart on The Big Bang Theory! This is a photo from "The Proton Displacement."
Dr. Proton and Bill Nye the Science Guy both visit The Big Bang Theory. "The Proton Displacement" is the seventh episode of the show's seventh season.

The Big Bang Theory Season 7 Episode 7 Quotes

Sheldon: No, go ahead, say it. I know what it is. I've heard it my whole life. The word's "annoying." Go ahead, say it. Say it. Say I'm annoying.
Amy: Sheldon...
Sheldon: Oh, it won't hurt my feelings. Go ahead, Amy, say I'm annoying. I'm annoying. I'm annoying. I'm annoying.

Dr. Jeffries: Hold on. You ... you have a girlfriend?
Amy: Hey look -- we're wearing the same orthopedic shoes. I can't believe I dress like a celebrity.
Dr. Jeffries: O-Okay, I get it now.