Skip Navigation
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Ever wondered why the sky is blue? Or why sunsets are red?

Scientists have found out the answers to questions like these.

Blue Skys

Hot air balloons in the sky

The light from the Sun is really made up of all the colors of the rainbow. Light energy travels in waves, like waves in water. Blue light waves are shorter than light waves of any other color.

Sunlight is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.

Red Sunsets

When the Sun is lower in the sky, sunlight goes through more of the atmosphere. The blue light is scattered so much that the reds and yellows pass through to your eyes.

Dust, pollution, and haze in the daytime can make the sky look grayish or even white, and sunsets look less colorful.

A volcano can throw huge amounts of dust and sulfuric acid droplets (tiny drops) high into the atmosphere. After a very large eruption of a volcano, sunsets around the world will be more colorful for many months.

Illusion
Other stuff you might like ...
Illusions
Can you believe your eyes?
Go!
What's That Word
Scientific Dictionary
Not sure of what a word means?
Find Out!
an open book with the letter a over it
Back to Top