What Causes the Change in Color in the Sky at Sunrise and Sunset?

Quck answer

During sunrise and sunset, the sky changes color due to the scattering of sunlight by Earth’s atmosphere. When the sun is low on the horizon, its light has to pass through more of the atmosphere, causing the shorter blue and green wavelengths to scatter away. This scattering phenomenon is called Rayleigh scattering, which leaves behind longer wavelengths like red and orange, giving the sky its vibrant colors. Additionally, particles and pollution in the air can also affect the colors observed during sunrise and sunset, creating variations in the hues and intensities of the sky.


Have you ever witnessed the sunrise or sunset? If you have, you must have been captivated by the vibrant reds, pinks, and purples that fill the sky as the sun rises or sets on the horizon. Have you ever wondered about the origin of these beautiful shades and why they are not visible throughout the day?

Interestingly, those colors are always present in the sky! However, they are not visible to us. How is this possible? The light that enters our atmosphere is initially white, containing all the colors of the rainbow. However, gas molecules in the atmosphere cause the light to break into different colored waves. Each color of light moves at a different speed. The colors that we perceive depend on the path of the light and the sensitivity of our eyes.

The gas molecules scatter the light waves in various directions, a process known as scattering. Sunlight scatters multiple times before reaching our eyes. Blue light, for instance, travels faster and scatters more frequently compared to other colors. This is the reason why we do not see the vibrant colors of the sunset during the day; the blue light scatters to such an extent that it conceals most other colors. However, at sunrise and sunset, when the light has to travel a greater distance to reach us, other colors manage to peek through. As a result, the other colors of light waves scatter more frequently during these times.

Interestingly, did you know that the sky could potentially appear purple? Purple waves move faster than blue ones, causing more purple light to scatter in the sky. However, our perception of colors is influenced by the sensitivity of our eyes. The peak of human eyesight falls in the middle of the rainbow, and since blue is closer to the center than purple, we see a blue sky rather than a purple one.

If you have observed multiple sunsets, you might have noticed that they are not always the same. What causes this variation? Some people claim that the most stunning sunrises and sunsets occur during autumn and winter, when the atmosphere is dry and allows light waves to travel at a higher speed. However, there are several factors that can influence sunsets by introducing new gas molecules into the air.

For instance, volcanic eruptions release debris into the atmosphere, causing light waves to scatter at a higher rate. Consequently, a sunset following an eruption appears as a glowing orange sky.

Pollution also impacts the appearance of the sunrise or sunset. In densely populated cities, pollution from vehicles blocks many shades of light. Consequently, sunsets in highly polluted areas only display a bright red color instead of a range of colors.

Lastly, clouds play a role in the appearance of a sunrise or sunset. One might assume that clouds would obstruct the view of the event. However, a few clouds in the sky enhance the beauty of the sunrise or sunset. These clouds capture the colorful rays as the sun rises or sets, resulting in the colors spreading higher into the sky.

Have you ever watched the sunrise over the ocean on a cloudy morning? What about witnessing a sunset on the horizon after a volcanic eruption? Many people believe these are the most breathtaking sights in the world. How does the sunset appear from your home?

Give It a Try

Are you ready to continue exploring? Enlist the help of a friend or family member for these activities!

Explore the Beauty of Sunsets and Sunrises

  • Observe the sunset with a companion and discuss the reasons behind the changing colors in the sky. Ponder upon why these colors are not always visible and why they can be seen at this moment.
  • Marvel at the stunning sunrises and sunsets captured from various locations around the world! Share with a friend or family member the place you desire to visit the most and explain the reasons behind your choice.
  • Thanks to NASA, delving into the electromagnetic spectrum has become effortless! Which new types of waves have you discovered? Write a paragraph highlighting the similarities and differences between visible light and another type of wave.

References for Further Wonder

  • https://news.nationalgeographic.com/news/2013/10/131027-sunset-sky-change-color-red-clouds-science/ (accessed 6 Feb., 2019)
  • https://www.livescience.com/34065-sunrise-sunset.html (accessed 6 Feb., 2019)
  • https://www.scientificamerican.com/article/fact-or-fiction-smog-creates-beautiful-sunsets/ (accessed 6 Feb., 2019)
  • https://www.spc.noaa.gov/publications/corfidi/sunset/ (accessed 6 Feb., 2019)

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