Why Do Pennies Turn Green? | Create with #MetKids Microscope

Pennies turn green when they get old because they have a special kind of friendship with water and air.

When you look at a brand-new penny, it's shiny and brown, like the inside of a chocolate bar. But over time, especially if it gets wet, like when you drop it in your juice box or it rains on it, something happens to its surface. It starts to react with the water and the air around it.

Imagine the penny is wearing a coat made of copper. Copper is what makes pennies feel rough under your fingers, like sandpaper. But when the penny meets water and oxygen from the air, kind of like a tiny party, it starts changing colors. The copper turns into something new called verdigris, which feels slick and looks green, like the color of a lime or a leaf in spring.

It's not magic, it’s just the penny having fun with the water and air!