This is the full version of the famous picture of Einstein sticking out his tongue, taken on March 14, 1951 after an event at Princeton University celebrating his 72nd birthday.

While walking with Dr. Frank Aydelotte, the former head of the Institute for Advanced Study, and Mrs. Aydelotte back to their car, a crowd of photographers and reporters followed them to get shots of Einstein.

UPI photographer Arthur Sasse, apparently the most persistent of the bunch, drew near to the car after the throng had disbursed and said, “Ya, Professor, smile for your birthday picture, ya?”

Assuming the photographer wouldn’t be fast enough, Einstein stuck his tongue out and then quickly turned his head away.

UPI editors debated on whether or not to use the picture. Sasse himself later recalled that “Caveo Sileo, assignment editor, liked it, but the chief editor didn’t. So they had a conference with the big chiefs upstairs. The picture got okayed, and we used it.”

Since Einstein had a reputation for being rather eccentric, the photo was seen as one that demonstrated his charm. The photograph soon became the most popular ever taken of him. In fact, it was Einstein himself who wanted it cropped into the version for which it is best known today, liking it so much that he sent friends greeting cards that were adorned with the image.

Einstein requested nine copies from UPI for personal use, one of which he signed for a reporter. On June 19, 2009, the original signed photograph was sold at auction for nearly $75,000.