The Sun at the edge of the day

At sunrise and sunset, the Sun looks red or orange. At noon it looks white. The horizon is the line where sky seems to meet ground.

Slide the Sun down. Watch how much blue and red remains.

The rule

Overhead, sunlight crosses little air.

Near the horizon, sunlight crosses much more air. More blue scatters out. The red light that is left makes the Sun look red. Red light scatters less than blue, so more red reaches your eye.

Never look at the Sun to check this. Watch the colour on clouds and walls.

The air also makes the Sun look higher

The air bends sunlight downward as it goes through. So the Sun looks a little higher than it is. At sunrise, we see the Sun about 2 minutes early. At sunset, we see it about 2 minutes late. For those 2 minutes, the Sun is really just below the horizon.

The same bending flattens the Sun's disc a little near the horizon.

Try the lab to finish this lesson.