Who's missing in this 50-year-old Apollo 11 photo?

What make this picture so profound? It shows the Eagle lunar lander returning from the first visit to the surface of the Moon on the Apollo 11 mission. But also, it includes ALL of humanity in the frame of the picture except for Michael Collins, the photographer. He took this picture 50 years ago, 21:34 UTC, July 21, 1969. (NASA Photo ID: AS11-44-6642).

He's the only person not included in the frame of this picture!

Imagine what it would have been like if they had social media back then. He probably would have taken a selfie, so he wouldn't be the only one left out of the picture. And he would have posted it on Twitter and Instagram.