Why are sunsets red?
Sky's Color Filter
Why are sunsets red?
You've seen it a thousand times: the sun drops toward the horizon, and suddenly the whole sky is on fire. Oranges, pinks, reds — colors that weren't there at noon. What changed? The sun is the same star it was three hours ago. So why does it paint the sky like this at the end of the day?
The answer is hiding in something you can't see: air. Miles and miles of it, stacked up between you and the sun. Air looks empty, but it's actually packed with tiny molecules — nitrogen, oxygen, little bits of dust. At noon, sunlight zips straight down through a thin layer of this stuff. At sunset, the light has to travel sideways through much more air to reach your eyes, like a swimmer crossing a pool the long way instead of diving straight to the bottom.
