Recognize this photo? Here’s the story behind it. On March 14, 1951, Albert Einstein’s 72nd birthday, United Press photographer Arthur Sasse was trying to persuade him to smile for the camera, but having smiled for photographers many times that day, Einstein stuck out his tongue instead. Editors were initially reluctant to publish the image, however once they did Einstein enjoyed the lighthearted photo so much that he ordered several copies to share with friends. It is considered one of the best known press photographs of the 20th century and one of the most popular images of the famous scientist.