Our Place in Space - Model/Drawing (Life Beneath the Surface)
Overview
Children build a second model - a planet whose surface is hostile to life but whose sub-surface environment a mile or two down can support life. They conclude by discussing questions about what planets and moons scientists consider possible places for extraterrestrial life and whether extraterrestrial life is more likely to exist on or below the surface in these places.
What's the Point?
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Life requires certain conditions, which are characterized by a set of factors.
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Important habitability factors are water, energy, nutrients, atmosphere, and temperature.
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Surface life requires an atmosphere to retain heat, provide chemicals needed for life (e.g., CO2), and shield the surface from harmful radiation (e.g., ultraviolet light).
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Scientists think extraterrestrial life is most likely to exist below a planet's or moon's surface.
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Scientists think life might exist (May 11, 2005/div>
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Organisms living far below the surface are single-celled microbes.
Materials
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Craft materials for constructing 3D models (clay/plasticine/Play Doh, cloth scraps, plastic bags, colored papers (e.g., wrapping paper, newspaper, construction paper), aluminum foil, straight pins for attaching elements to clay, glue guns, etc.)
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Craft materials for drawing or making a collage (colored crayons/markers/pens/pencils/paint, white paper, glue for paper, colored papers, scissors, tape (single and double sided), etc.)
Activity
7. Have children apply their understanding of habitability factors by using the craft materials to construct or draw a cross-section of a planet whose surface is hostile to life but whose sub-surface environment a mile or two down can support life.
- Remind children that the "What Makes a World Habitable" sheet can help them develop a suitable sub-surface environment.
- Give them 10–15 minutes to create their planet.
8. Reconvene the group and process their models/drawings. Call out a habitability factor. Go around the room and have each team describe in turn where this factor is found on its model or drawing. Do this with all five factors. After reviewing all five factors, ask teams to share any special features of their worlds.
9. Discuss the following questions:
- If life exists beyond Earth in our solar system, is it more likely to be life that lives on or below the surface? (Below)
- What size organism is best suited to life far beneath the surface? (Single-celled life)
- Why is a hot interior necessary for life far underground? (Heat circulates water. It can also melt and circulate minerals, bringing them close enough to organisms to be useful.)
- What might become a problem for life far below the surface? (Becomes too hot for life.)
- In the solar system, which planets or moons do astrobiologists think are promising places for finding life (or signs of past life)? (Mars and Jupiter's moons Europa & Ganymede)
Follow-Up Questions
- Research life found below the surface, such as at sea-floor vents, subterranean caves, and in rock layers a mile or two below the Earth's surface.
- Find out more about the search for extraterrestrial life on Mars and on Jupiter's moons.
May 27, 2009
