With the increased use of artificial intelligence images, there has been a proliferation of fake photos—particularly deepfakes. So how can we know when we are looking at a picture of a real human’s face? The answer may be in the eyes, according to recent research by astronomers, who theorized that analyzing human eyes in the same way that astronomers study pictures of galaxies: it’s all about the reflection in a person’s eyeballs, and it’s a matter of physics: If the reflections match, the image is likely that of a real human. If they don’t, they are probably deepfakes.