Why Does the Sky Change Color at Sunset?

At sunset, the sky changes color because sunlight has to travel through more of Earth’s atmosphere. Think of it like a big filter: when the sun is low, its light passes through more air, scattering blue and green light away. What's left? Red, orange, and pink, the colors you see in the sky. It's like when you shine a flashlight through a cup of water; the farther it goes, the more the light changes.