Professor Kettlewick
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Professor Kettlewick and Archimedes rising over the rooftops in the brass balloon
Episode 1 · 6 minutes

Colours of the Sky

Why Is the Sky Blue? Sunsets, Rainbows and the Sky on Mars

Why is the sky blue? Professor Kettlewick and Archimedes, his clockwork owl, take the brass balloon up to find out. Then Isla and Ollie see a sunset in a glass of water, Ollie makes a rainbow with the garden spray (the professor gets very wet), and everyone guesses what colour the sky is on the Moon and on Mars. Episode 1: Colours of the Sky.

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  1. 0:00Staring at the sky
  2. 0:26Opening titles
  3. 0:55Why is the sky blue?
  4. 2:21Why are sunsets orange?
  5. 3:46Make your own rainbow
  6. 4:52The sky on the Moon and Mars
  7. 5:49What a day!

The big questions

Try this with a grown-up

Science from the episode that you can do at home.

A sunset in a glassFrom Episode 1: Colours of the SkyMake a rainbow in your gardenFrom Episode 1: Colours of the Sky

Archimedes’ Fact File

On Mars, the daytime sky is a dusty butterscotch colour. And the sunsets... are blue.
Make a Rainbow in Your Garden!A 30-second Short from Episode 1
The Short

Make a Rainbow in Your Garden!

Ollie makes a rainbow in the garden with a hose! With the sun behind you, every tiny drop of spray acts like a little prism and splits the sunlight into all its colours. Just don't point it at the professor. Archimedes, the clockwork owl, does not enjoy baths.

Read alongEvery word of the episode, 37 lines
  1. 0:00

    Archimedes (telling the story): This is a story about the sky. It is mostly blue, sometimes orange, and, by the end, rather wet. If you would prefer a story about something drier, I suggest a biscuit.

  2. 0:12

    Professor: Archimedes! You've been staring at the sky all morning!

  3. 0:20

    Professor: Why is the sky blue? Ooh, what a splendid question!

  4. 1:00

    Professor: Hold on to your feathers, Archimedes. Let's go and see for ourselves!

  5. 1:07

    Professor (telling the story): Sunlight looks white... but it's really every colour, all mixed up together!

  6. 1:16

    Professor: Look! Red, orange, yellow, green, blue and violet!

  7. 1:24

    Professor (telling the story): Every colour travels in waves. Red's waves are long and lazy. Blue's waves are short and wiggly!

  8. 1:35

    Professor (telling the story): Our air is made of teeny, tiny bits, far too small to see.

  9. 1:42

    Professor (telling the story): When the wiggly blue light bumps into them, it bounces off... in every direction! Bing! Bong! Boing!

  10. 1:53

    Archimedes: Scattering. A long word for light bouncing about, like a marble in a biscuit tin.

  11. 2:00

    Professor (telling the story): So blue light is bouncing all over the sky, and wherever we look, it comes to our eyes.

  12. 2:14

    Professor: And that is why the sky is blue! Now, home we go, before...

  13. 2:21

    Archimedes (telling the story): He was going to say, before tea. But the sky had other ideas.

  14. 2:30

    Professor: At sunset, the light travels through lots more air. The blue gets bounced away... and the reds and oranges glow through!

  15. 2:45

    Professor (telling the story): At midday, sunlight drops straight down, a short hop through the air. At sunset, it skims sideways through miles of air, losing a little blue with every mile.

  16. 2:57

    Isla: Professor! The whole sky has gone orange! Did you break it?

  17. 3:04

    Professor: Break it? Ha! No, no, no. Come inside, and I'll show you a sunset in a glass of water!

  18. 3:12

    Professor: Try this with a grown-up! Shine a torch through a glass of water with a drop of milk. From the side it looks blue, like the sky. From the end, it glows orange, like a sunset!

  19. 3:30

    Ollie: Professor, what colour is the sky on Mars? I bet it's red. Everything on Mars is red.

  20. 3:38

    Professor: Tomorrow, Ollie, we'll find out. But first... we need some rain.

  21. 3:46

    Archimedes (telling the story): The next morning, there was no rain at all. So Ollie decided to make some. I mention this so you can move a little further from the screen.

  22. 3:57

    Ollie: Sun behind me, spray in front of me. One homemade rainbow, coming up!

  23. 4:04

    Professor (telling the story): With the sun behind you, every tiny drop of spray acts like a little prism, and out pops a rainbow!

  24. 4:14

    Professor: Ollie! Point it at the garden, not at the professor!

  25. 4:21

    Archimedes: I am a clockwork owl. I do not enjoy baths.

  26. 4:27

    Isla: Look closer! Every little drop on this leaf has its own tiny rainbow.

  27. 4:34

    Professor (telling the story): Inside every raindrop, sunlight bends, bounces, and comes out split into colours. Red, orange, yellow, green, blue and violet!

  28. 4:46

    Archimedes: Refraction. A long word for light changing its mind.

  29. 4:52

    Professor: Here's a puzzle for you. Can you guess what colour the sky is on the Moon? Have a think!

  30. 5:06

    Professor (telling the story): Black! Even in the daytime. The Moon has no air, so there's nothing for the blue light to bounce off.

  31. 5:16

    Ollie: And Mars? Is the sky on Mars red? Please say red!

  32. 5:22

    Archimedes (telling the story): Archimedes' Fact File. On Mars, the daytime sky is a dusty butterscotch colour. And the sunsets... are blue.

  33. 5:35

    Ollie: Blue sunsets? That's brilliant! I'm going to Mars. Tomorrow. In my teapot rocket!

  34. 5:42

    Isla: Then I'm coming too. Someone needs to check that teapot for leaks.

  35. 5:49

    Professor: So! Blue skies, orange sunsets, a rainbow in every raindrop, and a black sky on the Moon. What a day!

  36. 5:58

    Professor: Keep asking questions! See you next time with Professor Kettlewick!

  37. 6:06

    Archimedes (telling the story): It took three days for the professor's socks to dry. I counted.

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