It’s because the actual sky is so large. When you look at the moon in real life, your eye focuses on it so it takes up more of your visual field. Try looking straight up and doing a 360° and you’ll notice just how large the sky actually is.
When you photograph the moon, especially with a wide-angle lense, it doesn’t fill the visual field as much because it maintains the objective proportions of everything within it, and projects that onto a flat image. So when you see it on a screen, it looks smaller because you hadn’t previously noticed how small the moon is relative to the sky itself.
It’s because the actual sky is so large. When you look at the moon in real life, your eye focuses on it so it takes up more of your visual field. Try looking straight up and doing a 360° and you’ll notice just how large the sky actually is.
When you photograph the moon, especially with a wide-angle lense, it doesn’t fill the visual field as much because it maintains the objective proportions of everything within it, and projects that onto a flat image. So when you see it on a screen, it looks smaller because you hadn’t previously noticed how small the moon is relative to the sky itself.