Lunar and Planetary Institute

Space Radiation - UV Man in Space
EXPLORE! Health in Space

Space Radiation - UV Man in Space


Children ages 8–13 investigate how Earth's atmosphere protects UV Man! — and us! — from harmful ultraviolet radiation in this 60 minute activity. They continue the investigation with UV Man! in space, to determine what will happen to him without the protective blanket of Earth’s atmosphere, and create a capsule to protect him.

What's the Point?

  • Ultraviolet radiation from the Sun travels through space
  • The blanket of Earth's atmosphere protects us from much of the Sun's ultraviolet radiation
  • Without protection, ultraviolet radiation would be very harmful to people living and working in space


For each group of 4 to 5 children:

  • 1 UV Man! (in a shirt or poncho)
  • Cotton batting – poly-fill does not work as well (enough to make a square about 12" x 12")
  • Spray bottle with water, set on mist
  • A few drops of red and blue food coloring, to tint the water purple (optional)

For each child:

  • 1 UV Man!
  • Craft items to construct and decorate a space capsule for UV Man! For example, paper towel tubes, egg cartons, small boxes, milk cartons, aluminum foil, paint, markers, old CDs, construction paper, pipe cleaners, etc.
  • Rocket template (optional)

For the facilitator:


  • The children will be spraying a small amount of water, so you will need to locate this activity in an appropriate area.
  • Pre-fill the spray bottles with water and add a few drops of red and blue food coloring to tint the water purple.
  • Ensure that all sprayers are set on "mist."
  • Pull the cotton fluff to form a thin layer.


1. Introduce the concept that the Earth's atmosphere protects us from ultraviolet radiation.

  • What provides UV radiation to Earth? The Sun
  • How does it reach Earth? It travels from the Sun to Earth.
  • How do we protect ourselves from too much UV radiation? Clothing, sun block, staying inside.
  • What else naturally protects us from most of the incoming UV radiation? The atmosphere. Just like clouds can block some of the visible light on a rainy day, the outer layer of our atmosphere acts as a filter and filters out much — not all — of the UV radiation.
  • Why might UV radiation be a concern in space? Because there is no atmosphere in space to provide a protective blanket.

2. Invite the children to take turns placing their UV Men on a table or the ground, and then hold the atmospheric blanket (cotton fluff) about six inches over him. Ask them:

  • What do you think the cotton fluff represents? The cotton fluff represents the protective blanket of the Earth's atmosphere.

3. Have them hold the spray bottle about 6 inches from the atmosphere and spray 5 or 6 times. Invite their observations.

  • We are not using the mist to represent rain, what else do you think the mist represents? The mist represents ultraviolet radiation from the Sun.
  • Predict whether any of the "radiation mist" got through the Earth's atmosphere to UV Man!

4. Invite the children to uncover UV Man!

  • Were their predictions correct? UV Man! probably received a few sprinkles of the Sun's "UV radiation". Our atmosphere protects us from much, but not all, of the Sun's UV radiation.
  • What do the children expect will happen if UV Man! travels into space? Will he have the protection of Earth's atmosphere?

5. Have them experiment by taking UV Man! up beyond the cotton fluff atmosphere. Have one child in each group hold UV Man! at arm's length and have another child hold the spray bottle about 6 inches from UV Man! and spray him 5 or 6 times.

6. Invite the children to reassemble as one large group. Ask them what they observed when UV Man! traveled in space.

  • Were your predictions correct? If you said UV Man! would receive a lot more "radiation in" space, then you were right!
  • So, would an astronaut working outside the rocket in space receive a much bigger dose of radiation than if he or she was on Earth? Yes! Astronauts must take special precautions to protect themselves from UV radiation in space.
  • How might astronauts protect themselves in space? Wear a space suit, travel in a space craft.

Explain that Earth's atmosphere protects us from many of the dangerous types of radiation from our Sun — ultraviolet, X-rays, gamma-rays, and very high energy cosmic rays. We know that some ultraviolet radiation still gets through, but we can protect ourselves by covering up, limiting our time in the Sun, and using sunscreen.

Astronauts, however, live and work above Earth's atmosphere, so they could be exposed to very dangerous levels of ultraviolet radiation — and other types of radiation traveling from our Sun and from elsewhere in our galaxy and universe. They, too, must take precautions. They work in spacecraft that have special shielding, wear special suits when they work outside of the spaceship, and even have special visors to protect their eyes. Even with all of this protection, some high energy radiation can still pass through the shielding. Astronauts wear instruments, called dosimeters, that monitor how much radiation each of them has received. Once they reach certain levels, they do not continue to work in space.

And just like the children worked hard to find which materials would protect UV Man! from ultraviolet radiation — and some protected him better than others — NASA tests all sorts of materials and coatings for spacecraft and space suits to protect the astronauts.

7. Invite the children to use the craft items to construct a spaceship for their UV Man! When they have finished, have them spray the spaceship a few times to see if it successfully blocks "radiation".


Invite the group to share what they have learned about ultraviolet radiation on Earth and in space. What helps protect Earth from most of its harmful effects? How is ultraviolet radiation a challenge to astronauts? What do you think are some ways for astronauts to protect themselves from UV radiation? What happens to astronauts — and kids — who receive too much UV radiation?

Last updated
February 9, 2010

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