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        Where to Look for Life

        Students examine 12 cards that describe the planets and six moons in terms of their temperature and atmosphere and the availability of water, energy, and nutrients. Based on their assessment of the habitability, students identify the top candidates for life in the solar system.

        Lesson Summary

        Overview

        Students examine 12 cards that describe the planets and six moons in terms of their temperature and atmosphere and the availability of water, energy, and nutrients. Based on their assessment of the habitability, students identify the top candidates for life in the solar system.

        This activity was adapted from:
        What Makes a World Habitable? | NASA Astrobiology Institute
        Activity 3 in Life on Earth ... and Elsewhere? (pages 23–36).

        Objectives

        • Explore a theory held by many scientists, that habitable conditions exist beyond Earth and that the solar system offers several possible places that may be (or have been) able to support life.

        Grade Level: 1-6

        Suggested Time

        • One class period (approx. 20 to 30 minutes)

        Media Resources

        Materials

        Before the Lesson

        • Print the Habitability Cards (PDF).
        • Cut cards apart. To make them last longer, print them on card stock or laminate them.

        The Lesson

        Part I: Engage

        1. Ask:

        • Who can tell us how to play hide-and-seek? (Someone hides. Then others try to find that person.)
        • Why might looking for life in the solar system be like a game of hide-and-seek? (If there is life beyond Earth, it is not obvious. It is probably very small and living underground. Our challenge is to find it.)

        2. Tell students that in this activity, they are going to help decide where we should focus our search for life in the solar system.

        Part II: Facilitate

        3. Tell students that sending spacecraft out to look for life is very expensive. Plus, looking everywhere takes a long time. To decide where to look first, scientists narrow their search by understanding what makes a planet or moon habitable. They look closely at the most habitable places.

        Review what life needs and either refer to the list you made in Home Sweet Home, or have students call out the key requirements, such as food, water, suitable temperatures, and protection from harmful radiation. Make sure students are aware of food’s dual role as a provider of energy and of nutrients.

        Distribute the Habitability Cards (PDF) and point out that each card has images and evidence for how habitable a planet or moon is by giving information about its temperature and atmosphere and the availability of water, energy, and nutrients.

        Prioritize the cards. Have students use the Habitability Cards (PDF) to assess a planet’s or moon’s chances of supporting life, past or present. Have teams sort the cards into three piles: a likely, an unlikely, or a possible place for life. Use the Where to Look for Life presentation slides as you explain how to play the game. Ask them to be able to explain the reasoning behind their choices. (Note: For younger students, consider doing the sorting as a full-group activity.)

        Check for Understanding

        Rate each planet and moon by making a Habitability Chart (PDF) chart on a board. Go down the list, and have each team report its ranking and reasoning.

        Remind students that:

        • The same processes that forged life on Earth are found throughout the universe.
        • Except for Earth, each planet or moon currently has major limitations for life, as we know it.
        • Looking for habitable conditions is easier than looking for actual organisms.

        Ask students to name their top destination for the next space mission looking for life. (Europa, Mars, Callisto, Enceladus, and Titan may have or have had habitable conditions.) Use the Where to Look for Life presentation slides to show images of the likely and possible candidates for life. Then visit the most promising candidates for life (Enceladus, Mars, Europa, and Titan) by showing one or more of the NOVA video resources, and using the provided discussion questions to further engage students in the video content.

        Keep Exploring

        The search for life (Optional)

        The American Museum of Natural History's Search for Life guide, found in the online index, explains the five components of habitability: distance and energy, a protective shield, proper temperature range, water, and the right ingredients. Further explain these concepts to students and then discuss how life on Earth would be affected by several changes proposed in the guide.

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