Sunrise and Sunset

Sunrise over Liverpool, UK
Credit: Dave Wood

The Sun appears above the horizon each day. This happens not because the Sun is moving, but because the Earth spins on its axis. We see the Sun rise in the east and set in the west. This is because the Earth is rotating from west to east (if you were looking down from above the North Pole). 

The Earth is a sphere. This means sunrise cannot happen at the same time all over the Earth. The time the Sun rises and sets depends on where you live in world. And because the Earth is tilted on its axis, sunrise and sunset times also depend on the time of year.

The colour of the sky changes at sunrise and sunset. During the daytime the sky looks light blue. This is because small particles in the atmosphere scatter the sunlight. Blue light is scattered more than red light due to its shorter wavelength. This is called Rayleigh scattering. Sunrise and sunset look redder because the light from the Sun passes through more of our atmosphere. The blue light is scattered so much we can't see it. This leaves the longer, redder wavelengths of light. Did you know all parts of the electromagnetic spectrum can be scattered by the atmosphere?