An illusion of a portrait. It holds your attention and makes you examine it. At first the man's face appears to look like it's only half of his face is showing, but once you look at it, you notice that it's also a profile view of the man's face. I think it's a clever and classic design example.
This photo is very interesting because it looks so real, making it seem like the earth is in our hands and we need to take care of it. There are a lot of questions that could be asked about it but i think this is really good. I couldn't find the source.