Children ages 8–13 construct UV Man! (or woman or dog!) and equip him with special radiation detectors to investigate the source of ultraviolet radiation in this 60 minute activity. They explore how we can protect UV Man! — and ourselves! — from being exposed to too much UV radiation.
For each child:
Sources for UV Beads:
Educational Innovations
Phone: 1-888-912-7474 / Fax: 203-229-0740
Steve Spangler Science
Phone: 1-800-223-9080
Sundance Solar
Phone: 603-456-2020 / FAX: 603-456-3298
Introduce the topic of solar radiation. The children may be unfamiliar with UV radiation and its effect on skin; you may need to lead them through the discussion.
2. Invite participants to construct a UV Man! (or woman or dog!). Explain that they will equip him with radiation detectors (UV beads) that are made from a special pigment that is very sensitive and turns colors when exposed to the ultraviolet rays. With the help of UV Man! they will investigate the source of ultraviolet radiation and how we can best protect UV Man! — and ourselves! — from it.
To construct one UV Man! (or woman or dog!):
3. When the children finish, ask them what they observe.
4. Ask the children to cover UV Man’s radiation detectors with their hands so that no light can get in, and then take him outside. Have them stand in the shade and uncover their UV Man! What do they observe happens to UV Man’s radiation detectors? The beads become lightly colored if the children are standing in light shade, indicating that, even in the shade, there is some UV radiation reaching the detectors and our skin.
5. Ask the children to cover UV Man with their hands again so that no light reaches him. Keep UV Man covered for about 1 minute while the beads change back to white. Use this opportunity to discuss their observations.
6. Let the children now take UV Man! into the full Sun. What happens to the beads? The beads become deeply colored, reacting to the intensity of the UV radiation to which they are being exposed.
7. Return to the room and continue the discussion.
Some children may say light caused them to change, and others may say heat. Remind them of their observations about the beads inside; the beads were white, even though they were in the light of the room. Ask them what happened to their beads when they brought them back inside; the beads changed from a colored state in the Sun back to white in the room light. Light does not affect the beads. If it is heat that causes the change, invite the children to hold beads in their fists; the beads do not change color when heated. They can also heat the beads with a hair dryer. The cause of the change comes from the Sun; it is from the part of the Sun’s spectrum we do not see or feel directly.
8. Invite the children to protect UV Man! from UV radiation. Provide them with two materials to cover him or protect him in other ways. To get them started, have them make a construction paper poncho or shirt to cover the top UV bead. Have them test at least two additional ways to protect UV Man! by covering him with the materials you have provided. Have them take UV Man! outside again to test each material.
9. As a group, have the children share their experiments and observations.
10. Share with the children that with UV Man’s help they have demonstrated the effects of the Sun’s ultraviolet rays on objects (and people!) on Earth. In the next activities they will investigate a special characteristic of our planet that protects it from receiving even more UV radiation than it already does, and whether or not UV radiation is a challenge to living and working in space.
Ask the group to share their thoughts about ultraviolet radiation. Where does it come from? Is it dangerous? How can we protect ourselves from it?
Light and heat are part of the spectrum of energy — or radiation — our Sun provides. We can “see” light and we can "feel" heat. But there are other types of energy that our Sun produces. Much of this energy makes up the electromagnetic spectrum. Light is part of the visible section of the spectrum and heat is part of the infrared section of the spectrum. Radio waves, microwaves, ultraviolet rays, X-rays, and gamma-rays all are parts of the spectrum of electromagnetic energy — or radiation — from the Sun.
Radiation is energy that travels in waves or as particles. Radio waves, microwaves, visible light, and infrared radiation have relatively long wavelengths and low energy. But ultraviolet rays, X-rays, and gamma-rays have shorter wavelengths and higher energy. This shorter wavelength is so small that these wavelengths interact with human skin, and cells, and even parts of cells — for good or for bad!
Our Sun also produces cosmic radiation. Cosmic rays are very high energy, fast moving particles (protons, electrons, and neutrinos) that can damage DNA, increasing the risk of cancer and causing other health issues. Cosmic rays have such high energy that it is difficult to design shielding that blocks them, Cosmic rays do not only come from our Sun, but from other places in our galaxy and universe.
The subject of this activity is ultraviolet — UV — radiation. Humans need UV radiation because our skin uses it to manufacture vitamin D, which is vital to maintaining healthy bones. About 10 minutes of Sun each day allows our skin to make the recommended amount of vitamin D. However, too much exposure to UV causes the skin to burn and leads to wrinkled and patchy skin, skin cancer, and cataracts.
On Earth, we are protected by our atmosphere from most UV radiation coming from the Sun. The Ozone layer absorbs much of the UV portion of the spectrum (UVB and UVC). Some still gets through (UVA and a bit of UVB). We can protect ourselves completely by covering ourselves with clothing and using sun block. Our atmosphere protects us from most of the X-, gamma-, and cosmic radiation as well.
In space there is no atmosphere to protect astronauts from UV radiation — or from X-rays and gamma-rays, or even more dangerous cosmic rays. Astronauts have to provide their own protection in the form of space suits and space stations. These measures work very well for protecting against UV radiation, but the higher energy radiation is not completely blocked. Even with protective shielding, astronauts aboard the International Space Station receive a daily dosage of radiation about equal to 8 chest X-rays!
The UV-sensitive beads used in this experiment serve as UV radiation detectors. They contain a pigment that changes color when exposed to ultraviolet radiation from the Sun or from UV lights. The intensity of the color corresponds to the intensity of the UV radiation. When shielded from UV sources, or when exposed to light that does not contain UV radiation — such as indoor light bulbs — the beads remain white. The beads are designed for multiple use and, according to the manufacturers, will change color up to 50,000 times.
