Reflections on Ice: How We Look For Ice
What's the Point?
- 12 flashlights
- 2 UV lights (blacklights) (These may be purchased for under $20 each. UV light bulbs do not work as well)
- 1 sheet each of red, blue, and green colored gel (colored filters).
- 4 (6" wide and 2" deep or larger) containers (such as pans or trays) to hold water
- 1 box of food coloring (red, yellow, green, and blue)
- 1 ice cube tray
- 1 small spoon
- 1 bottle of tonic water (preferred) or 2 sheets of white copier paper (alternate)
- 6 sheets of cardstock
- Access to freezer
- Access to a dark room for the group activity
1. Introduce the activity by asking the children to share what they know about light.
- Where does our light come from? Lamps, flashlights, the Sun.
- Do planets make their own light? No! Planets, moons, asteroids, and other objects in our solar system reflect light. They reflect the light from the Sun. We see these planets in the colors of light they reflect.
- Is there light we cannot see?
Share with the children that there are many different kinds of light. Some we can see. Some we cannot see; it is invisible to us. All of these different types of light or electromagnetic radiation make up the electromagnetic spectrum.
2. Divide the children into groups of two to three and provide each group with the Amazing Electromagnetic Spectrum cartoon.
- What does the image show? It shows different parts of the electromagnetic spectrum, or different types of light.
- Which can we see? We see the visible parts of the spectrum — red, orange, yellow, green, blue, and purple. Each of these colors that we see is a different type of light.
- What are some other types of light that we cannot see? X-rays, ultraviolet rays, microwaves, and others.
- Have they had any experience with any of these types of light? Have they ever had an x-ray of their bones? What type of light does the x-ray machine use? Do they use a radio to listen to music? What type of light does their radio "see"? Do they use microwaves to heat their food? Have they seen a blacklight before? What types of light does a blacklight emit? (ultraviolet and some visible).
3. Share with the children that scientists use different types of light that are reflected off distant planets and moons to study the ice on those planets and moons. Explain that they will be investigating three different ice stations using different types of light.
4. Invite the children to investigate the ice! Arrange the children to work in groups. Explain that Ice Investigation Station sheets are located at each station to assist them in their investigations. Review with the children what they will be doing at the stations; let them know that the room will be dark during their investigations.
- At Ice Investigation Stations 1 or 2 the children will first examine the ice with their eyes only and draw and record what they see. They will then examine the ice using a flashlight, shone at different angles and in different areas of the ice sheet, then draw and record what they observe with the flashlight. At these stations, the children will observe such characteristics as bubbles, fractures, internal features, and spikes in the ice, and a white or clear color. They will observe finer details, and different details at different angles, with the flashlight. The point is that different amounts and angles of light can reveal different features.
- At Ice Investigation Station 3 or 4 the children will observe the ice using different colored flashlights. At these stations, when the children look at the different colored ices using flashlights covered with colored films, the ice that is the same color as the flashlight will appear bright and those with different colors will appear dark or even disappear. For example, red ice appears red because it is reflecting red light. When a blue light shines on red ice, the ice absorbs the blue light and there is no red light to reflect, so the ice appears dark. The point is that different colors or types (or wavelengths) of light can tell us about different types of ice.
- At Ice Investigation Station 5 or 6 the children will view and compare two pans of ice first with their eyes only. Next, they will shine an ultraviolet light — or "blacklight" — on both pans and record any differences they observe. At these stations, the children will not see much difference between the two pans of ice with their eyes, but will see that one pan "glows" with the blacklight. The point is that different types of light can reveal different information about ice's features and characteristics.
5. Instruct half of the teams to visit the even numbered stations and the other half of the teams to visit the odd numbered stations. Each team will visit three stations. Dim the lighting in the room and invite them to begin their explorations! Allow approximately 10 minutes for each station and let the teams know when it is time to rotate.
6. After all the children have had a chance to visit each station, invite them to share their discoveries. Prompt them with questions.
- Before they used the different lights or films, what did they observe about the ice with just their eyes?
- Was the ice the same everywhere — was it uniform? Or were there differences that their eyes could see?
The variations that occur in the icy surfaces of planets and moons — seen in visible or invisible light — are very important. They can hold clues to how the ice formed and what might be under the surface.
- What did they see that was different when they used the flashlights to illuminate the surface? Did different features "pop out?"
Remind the children that scientists are not shining big bright flashlights on the surfaces of planets. This would be very expensive (and also quite a challenge to the engineers!) Instead, scientists let the Sun's light help them. The Sun's light contains the visible colors that we see everyday, but also ultraviolet or infrared light. Scientists use special telescopes on Earth and instruments aboard spacecraft that are orbiting different planets and moons to study the different types of sunlight reflecting from the surface.
- Why might scientists want to study a planet when the Sun's rays are striking the surface at different angles? What did they see when they used the flashlights at different angles? Different angles of light caused different things to be revealed. When the light is shining directly on a surface, the surface can look flat. When the light is shining on a surface at an angle, you can see that the surface has lots of different features. These features cast shadows at low angles of light.
- What did the children observe about the different ices using the colored flashlights? What happened to the ices — did they look the same? Do the children think there was something different about the different ice pans? Some ice was bright under the red light and dark under the blue light, other ice was bright under the blue light but dark under the red light. Different colors of light made it easier to see the different types of ice.
- What did the children observe happening when they looked at the ultraviolet light reflected off the ice trays? Do the children think the ices were the same, or were they different? When the ultraviolet light shined on one of the ices, it appeared very bright revealing it had a different composition.
Ultraviolet light is invisible to the human eye, and yet some substances that we cannot see — or cannot see well — reflect ultraviolet light that can be detected by special telescopes and instruments aboard spacecraft.
Prompt the children to consider how scientists use light to study the surfaces of other planets and moons and how light can help them to determine if ice is present on the surfaces. Review with the children what they have learned.