What Causes Day and Night?

The sky changes color because light travels through the air. When the sun is high in the sky, it looks blue because most of the shorter blue wavelengths get scattered around. But when the sun is low on the horizon, like at sunrise or sunset, more of the longer red and orange wavelengths make it to our eyes, making the sky look warm and colorful.

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Examples

A child sees the sky turn orange while watching the sun set over a lake.
The sky looks blue in the afternoon but turns red when the sun is low on the horizon.
On a cloudy day, the sky can appear white or gray instead of blue.

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Categories: Science · light,sunlight,scattering,optics,atmosphere