Marking his first half-hour sitcom appearance in nearly a decade, comedy legend Bob Newhart will guest star on The Big Bang Theory this May, TVLine has learned exclusively.

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The six-time Emmy nominated star of The Bob Newhart Show and Newhart will play “Professor Proton,” the former host of Sheldon’s favorite science show as a kid. (We will come to learn that the Professor played a big part in the childhoods of both Sheldon and Leonard.)

According to a BBT source, Sheldon tracks his idol down online and discovers that he can be hired out for parties and events. Naturally, Sheldon books him to come to their house.

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The episode is slated to air on Thursday, May 2.

Big Bang Theory returns with its next original episode on Thursday, April 4.