Wonder Contributors

Several Wonder Friends inspired us to take another look at today’s Wonder, including Aliza from Canada, Kaleel from Illinois, and Divya from New Jersey.  Thanks for WONDERing with us!

The sunlight we see each day, called “white light,” may appear colorless, but it is actually full of a lot of colors mixed together. This is why you see a rainbow when you shine white light through a prism. The prism separates the white light into each of its colors: red, orange, yellow, green, blue, indigo and violet.

Each of the colors is made up of its own wavelengths, kind of like a unique fingerprint. Red has the longest wavelength, violet has the shortest and all the other colors are somewhere in the middle.

When you look at an object, such as a yellow sunflower or a red wagon, the color you see is actually the color of light the object reflects to your eye. A yellow sunflower reflects yellow wavelengths while absorbing all the other colors. A red wagon, on the other hand, reflects red.

So how does the air in the sky have a color? The Earth’s atmosphere is filled with gas molecules. As white light from the Sun passes through the atmosphere, colors with longer wavelengths, such as red, orange and yellow, pass through. Blue and violet wavelengths, on the other hand, are absorbed by the gas molecules and scattered across the sky. Your eye sees these reflected wavelengths as blue.

Of course, you’ve probably seen the sky turn brilliant shades of orange and red during a sunrise or sunset. When the Sun is low near the horizon as it rises or sets, the wavelengths have farther to go in order to reach your eyes. This causes the shorter blue wavelengths you see during the day to scatter even more, clearing the way for longer wavelengths like red and orange to reach your eyes.

90 Join the Discussion

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  1. Wow! This wonder was amazing, Wonderopolis! I never knew that the sky was blue because of the white light from the sun (that is actually full of many colors) and the blue wavelengths passing through the air cause the sky to turn blue! I always thought that the sky was blue because it was just blue! Now I know the real scientific reason! Also, it is so cool how a rainbow can be formed when you shine white light through a prism which separates the white light into seven sections! (red, orange, yellow, green, blue, indigo, and violet). This wonder was so cool! It really made me wonder!

    • Hello, Sarah! We’re super happy to hear that you now know the reason why the sky is blue! You sure learned a lot of facts about the sun, colors and wavelengths by exploring this Wonder of the Day®! That’s a LOT of WONDERing…way to go! :-)

  2. This is a wonder that I have been wondering about, too. I hit the jackpot! This is sooooo cool. I never knew it was because of white light!

    • Thank you for leaving us this awesome comment and for letting us know you “hit the jackpot” by exploring this Wonder of the Day®, Kaley! You’re a GREAT Wonder Friend! :-)

  3. I think I have read more than 5 wonders this day. It’s very cool and awesome! My curiosity is increasing! I want to spend a lot of time in wonderopolis. Lots of luck to wonderopolis!!!

    • Thanks so much for the good luck wishes, Amoolya! We have really enjoyed reading all your great comments and are super happy to hear that you think Wonderopolis is cool and awesome! :-)

    • It makes us super happy to read comments like yours, 13! We really like when our Wonder Friends let us know they understand a little bit more about something they have WONDERed by exploring a Wonder of the Day®! :-)

  4. I always wondered about this! Thanks for the explanation! I love this website, too! My teacher showed me it today on her website.

    • We think it’s 100% AWESOME that this Wonder features something you’ve always WONDERed about, Taylor! We love hearing when that happens! Please tell your teacher we think she ROCKS for sharing Wonderopolis with you and your classmates! :-)

  5. I never knew that sunlight is also called white light. I didn’t know that at sun rise and sun set the waves had to go farther to reach your eyes. I didn’t know that each color was made of different wavelengths. I never knew that red had the longest wavelength and purple had the shortest. Do you know what types of gas molecules are in the air to filter the waves?

    – Team Unger 14

    • Hello, Team Unger 14! Thanks so much for visiting this Wonder! We’re glad you enjoyed learning about light! :-)

  6. That’s funny how questions like this have such “complicated” answers. The universe in amazing!

    • Thanks so much for sharing your comment with us today, Wonder Friend SST, and THANK YOU for visiting Wonderopolis! :-)

    • Great question, Boom Cat! In the “Try It Out Section”, you will need a dark place and will be using the flashlight as the lighting over the glass. We’d love to find out how the experiment goes! :)

    • Hi there, Wonder Friend Julia! It’s cool to Wonder about all sorts of things… including blue skies! We hope you learned something new today! :)

    • Hey there, Wonder Friend Caira! Thanks for sharing your cool comment with us– we Wonder if you can write a story based on what you learned?! We think it would be awesome, just like you! :)

  7. sometimes I wonder if you could let real kids to figure out the wonder of the day and make a video to show kids what the answer is

    • Hey there, Wonder Friend! Thanks for sharing what you have been WONDERing about! We’re glad you are here today! HOORAY for WONDERing about the beautiful, bright sky! :)

    • That’s an awesome question, Quinn! We’re thrilled that you’re WONDERing with us about the color of the sky! Just like the red you see during a sunset close to the horizon, those long red wavelengths reach your eyes because it takes them longer to get there. We think it’s awesome that you’re WONDERing about how different the world would be if we woke up and saw a bright red sky each morning! :)

    • Thanks so much, Josiah! We’re so very glad you’re here to Wonder with us today! We hope the sky is bright blue and sunny for you today! :)

  8. When the earth rotates, it makes it harder to see the blue in the sky. When the sun goes down, why does it sometimes turn red?

    • Hi Kaleb! The sunset can appear red because the reaction of the light and the air with the sun. It’s pretty beautiful! Thanks for WONDERing with us! :)

  9. I have to be honest here—this is a concept I have never believed, nor will ever believe. If this were true, then a prism would show no color if the light is produced by a lightbulb or candle. Because the sun goes down, it doesn’t mean the world is colorless. It simply means we are unable to SEE the color in everything around us. The pigments in flowers, skin and everything else come from the thing itself. It is simply the light which enables us to see it, including what’s in our atmosphere. It is the cuts in crystal that enable the color, contained in the crystal itself, to be revealed as the light passes through it. It is the composition of the glass itself and what’s in it that produces the color. It is the cutting that creates the reflection which is why diamond cutting is an art and produces different effects depending on the cuts.

    Because glass “appears” clear, doesn’t mean that, at a molecular level, it is. Sand is not clear! Add color to the glass and that’s the color you see. Mix paint and the color is from the paint itself.

    As I said, I do not believe sunlight itself contains color. It simply reflects or enables us to see the color in everything, including the atmosphere.

    • Hi Donna! Thanks for sharing your thoughts. We are sorry you did not enjoy this WONDER. What we’ve presented here in this Wonder of the Day is the scientific explanation for why the sky is blue. There are LOTS of great WONDERS here on WONDERopolis. We hope you will check out other WONDERS and keep WONDERing with us! :)

    • Hi matthew! That’s a great question. Maybe you could do more research at your library. Thanks for WONDERing with us! :)

    • Hi Charity! We are glad you learned something from this WONDER and had fun too! Check back each day for a new Wonder of the Day! :)

        • Hi Taylor! We are sorry the video did not work for you. Hopefully it will next time. If not, we encourage you to watch it on a desktop computer. We are glad you enjoyed this WONDER and love your enthusiasm about WONDERing! :)

    • That’s an interesting connection, Alysa! Thanks for sharing with your WONDER friends! Keep up the great thinking and WONDERing! :)

  10. I learned that blue and violet wavelengths are absorbed by the gas molecules and scattered across the world and that is how we see a blues sky.

  11. I learned what makes rainbows which is white light makes too. And what makes the color of the rainbow and what reflects the colors. The sun light we seen every day is made of white light. Red is the is the longest and violet is the shortest.

    • Hi Trazazriya! That’s great you learned so much from this WONDER. Thanks for sharing your learning with us here at WONDERopolis! :)

  12. Wow! I’m kind of a science freak, so this info really amazed me. I also thought that the suns light was a red-orange ball of gas that exploded rays of fire every once and awhile, so this was really great. This is my first time reading a article on Wonderopolis, and I can’t wait to read more! This website rocks.

    • We are glad you discovered WONDERopolis, Taylor! Check back everyday for the new Wonder of the Day. There are also many previous WONDERS to explore here. Have fun and happy WONDERing! :)

  13. I learned that the violet and blue streams are scattered across the sky because, they have shorter streams. That makes the sky the blue it is today.

  14. The clouds have molecules that is vilet amd blue and that is how the clouds get thier coler and each of it’s colers was made up as it’s own wavelenth

    • Welcome, elexeanna! The Earth’s atmosphere has air molecules that absorb and reflect colored wavelengths. The molecules absorb the blue and violet wavelengths and scatter them across the sky, which our eyes see as blue. Thanks for commenting today! :)

  15. I learned that if there’s a yellow flower and light goes to it that it will reflect yellow light and absorb all the other colors.

  16. I learned that blue and violet are scattered across the sky that is why the sky is blue. I also learned that red has the longest wavelength and violet has the shortest wavelength.

    • Hi Tagan! We see the reflected wavelengths scatted across the sky as blue, which is why the sky looks blue. We are glad you learned so much from this WONDER! Thanks for visiting WONDERopolis! :)

  17. The white light makes a rainbow with a prism.If the the white light wasn’t white what will it make?And can a square make a color?

  18. I learned that if there is a yellow sun flower that if light goes to it yellow light will bounce off and all the other colors will be absorbed.

  19. The clouds has Molucles that is blue and vilot that is what gives the clouds coler and and the sunlight is made up of it’s own wavelengh

    • Hi elexeanna! The Earth’s atmosphere has gas molecules that absorb the blue and violet wavelengths and scatter them across the sky. We see the reflected wavelengths as blue. The sun is a “white light”. It looks white, but is made up of lots of colors. Objects absorb and reflect colored wavelengths, which allows us to see colors. WONDERful! Thanks for WONDERing with us! :)

  20. I learned that blue and violet are scattered across the sky that is why it is blue. I also learned that red has the longest wavelength and violet has the shortest.

    • We are glad you learned so much from this WONDER, Tagan! Thanks for sharing your new knowledge with your WONDER friends! :)

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Have you ever wondered…

  • Why is the sky blue?
  • What color is sunlight?
  • Why does the sky turn red and orange at dawn and dusk?

Wonder Gallery

hSunflowerdreamstime_xxl_20070647 (Custom)Vimeo Video

Try It Out

Grab a friend or family member and explore one or more of the following colorful activities at home:

  • Do you think you could get used to the sky being a different color? What if you were to travel to a distant planet in another galaxy? Suppose on that planet the atmosphere bent light in different ways, leading to skies that were green or purple. How might life change? Do you think it would affect your mood? Why or why not? Take some time to imagine what it would be like to live on such a planet. Share your thoughts with your friends and family members. Do they agree? What do they think life would be like?
  • Want to experiment with light at home? Why not jump online to check out How To Create a Prism? You’ll need just a few simple items, such as paper, aluminum foil and clear glass. Have fun separating light into its different colors!
  • Up for a challenge? Would you believe you can make blue skies and brilliant sunsets in a jar at home? It’s true! You will need the following items:
    • clear glass jar or a drinking glass
    • water
    • milk powder
    • flashlight
    • dark room

Fill your clear glass or jar with water and add about 1/2 to 1 teaspoon of milk powder and stir slowly. Turn off the lights and shine the flashlight on the surface of the water. Watch the water in the glass from the side near the flashlight. You may notice a bluish tinge. Now, hold the flashlight to the side of the glass and look through the water directly at the light. It will now look red. If you put the flashlight under the glass, the light will appear redder than before. Why does this work? The fat molecules from the milk powder in the water behave like air molecules. They scatter the light from the flashlight. When the light shines in the top of the glass, blue light is scattered and a bluish tinge can be seen out the sides. When you look through the water directly at the light, you peer through more of the milk fat molecules. This causes more scattering of the blue light and makes way for red wavelengths.

Still Wondering

Visit ReadWriteThink’s Explanation of a Weather Saying lesson to learn the explanation behind the old weather saying, “Red sky at night, sailor’s delight, red sky in the morning, sailor take warning.”


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