The Sun itself is not changing color every morning and evening. What changes is the path its light takes through Earth’s atmosphere before it reaches your eyes. Sunlight contains many visible colors mixed together, and the atmosphere does not treat every color exactly the same way.

During the middle of the day, the Sun is high in the sky, so its light passes through a shorter path of air. Much of the red, yellow, and green light travels through together and still looks nearly white or pale yellow to us. At the same time, the atmosphere scatters a lot of the shorter blue and violet light in many directions, which is why the sky looks blue.

At sunrise or sunset, the Sun is low near the horizon. Now the sunlight must travel through much more atmosphere before it reaches you. Along that longer path, more blue and violet light gets scattered out of the direct beam. What is left reaching your eyes from the Sun is richer in yellow, orange, and red.

A simple way to picture it is to imagine sunlight as a box of colored pencils. At noon, most of the pencils arrive together. Near sunset, the atmosphere has already tossed many of the blue pencils sideways into the sky, so the light coming straight from the Sun looks warmer.

Dust, smoke, pollution, water vapor, and other tiny particles can change the effect. NOAA explains that aerosols and dust can scatter longer wavelengths such as red light, and UCAR notes that fires, volcanic eruptions, and polluted air can make sunsets look more orange or red. That is why one sunset can look soft yellow while another looks deep red.

Clouds can add another layer. NASA notes that water droplets in clouds can make them appear bright white, while a low Sun can give clouds a golden hue. UCAR also notes that more particles in the air can make sky colors stronger. The color is not only about the Sun; it is also about what the sunlight meets on the way.

This is also why the Sun can look different from place to place. A dry desert, a smoky city, a clean mountain sky, and a humid coast can all put different particles and water vapor in the light’s path. The same Sun shines on all of them, but the atmosphere acts like a changing filter.

So the short answer is: the Sun looks different colors because sunlight is scattered by air molecules and particles, and the amount of atmosphere in the way changes through the day. High Sun, shorter path, paler color. Low Sun, longer path, more scattering, warmer reds and oranges.

References

1. Crepuscular Rays and Light Scattering – NASA Science
2. Why Is the Sky Blue? – NOAA NESDIS
3. Global Radiation and Aerosols – NOAA Global Monitoring Laboratory
4. The Appearance of the Sky – UCAR Center for Science Education
5. Rayleigh scattering – Britannica

Explore More

• Why is the sky blue instead of violet?
• Why do some sunsets look pink instead of red?
• Why does the Moon sometimes look orange?
• What is Rayleigh scattering in simple words?
• Why do clouds look white, gray, or red?