Program 3 Four Rocks near the Sun
Features and Planetary Processes (14:51)

Objectives
After viewing the video and participating in one or more of the Hands-On Activities suggested, students will be able to:

  •  discuss the similarities and differences between the 4 terrestrial planets of our solar system
  •  describe the key forces (e.g. size, distance from the Sun, greenhouse effect) which make these worlds different
  •  recognize "comparative planetology" as the discipline which helps us learn about Earth by looking at other planets

    Program Description
    Program 3 enables educators to address the 2 key science standards which require students to know the main features of the Earth, (Science Standard 1 "Understands basic features of the Earth"), and the processes which shape our home world and the other planets of our solar system. (Science Standard 2 "Understands basic Earth processes") Chris Chyba uses a down-home example of small and large potatoes in an oven to explain how size is a basic but critical factor in planetary formation and evolution: smaller planets cool faster. Claudia Alexander compares volcanism on Earth, Venus and Mars, and shows how plate tectonics shaped the chain of Hawaiian Islands. By comparing and contrasting how the greenhouse effect has impacted Venus, Earth and Mars, Chyba lucidly explains why liquid water is plentiful on our planet, but has vanished from the surfaces of Venus and Mars. (Please note that, as more fully described in program 4, recent images from the Global Surveyor spacecraft indicate that liquid water may still be able to exist for short intervals on the Martian surface. Yesterday's textbooks cannot keep up with the ongoing process of solar system exploration!) Please note: mathematically observant students may point out that the percentages of nitrogen and oxygen present in Earth's atmosphere shown in the program do not total 100%. Additional constituents include argon, carbon dioxide and smaller amounts of several other gases. (Also see program 7 for more images of the "Face on Mars"-in reality, a wind-eroded rock formation.)

  •  "Features of the Terrestrial Planets" (4:19) uses a simple video checklist to introduce some characteristics by which the four terrestrial planets differ: moons, craters, volcanoes and liquid water. Online you can find additional features by which to "compare and contrast" these planets such as length of day and year, presence and kind of "weather" (sulfuric acid "rain" on Venus and "dust-storms" on Mars), and more.
  •  "What Makes them Different?" (4:21) A look at how planets form and the most important processes which make the terrestrial planets into very different places. These include size and distance from the Sun, which, for example, make Mercury uninhabitable. Size and temperature also drive volcanism, which in turn shapes a planet's atmosphere.
  •  "Comparative Planetology" (1:17) returns to the theme introduced in Program 1: that while we cannot do controlled experiments to see what may happen to the atmosphere of our planet, we can learn from the histories and current conditions on those planets most like Earth-Mars and Venus. Comparative planetology may enhance our understanding of such complex issues as global climate change and eventually replace opinion with solid science.

    Vocabulary
    planetology, planetesimal (small planet-like body), spherical, Phobos (Greek for "Fear," a moon of Mars), Deimos (Greek for "Terror," the second moon of Mars), hemisphere, continental drift, plate tectonics

    Pre-Viewing Questions / Suggested Procedure for Program 3
    Paralleling the graphics used during the program, you may wish to have individual students, or 4 teams of students, make a chart or charts with headings for Mercury, Venus, Earth, and Mars. Allow adequate space for observations and notes, and have them jot down the characteristics of the 4 terrestrial planets during their viewing of the video. Students might research further in books or online after screening the tape, and include their reports in their Logbooks.

    Post-Viewing / Quiz Questions

  •  What force makes a large planet spherical, but allows an asteroid to be shaped like a potato or a peanut? (Gravity)
  •  Which planet has the shortest year in our solar system, and how long is it? (Mercury, 88 Earth days)
  •  Which of the 3 other terrestrial planets is closest to Earth in size? (Venus)
  •  Which of the 3 other terrestrial planets has almost the same surface area as Earth's dry land? (Mars)
  •  Name some of the spacecraft with names beginning with the letter "M" cited in this program! (Mariner 10, which studied Mercury; Magellan, whose radar peered through Venus' clouds-and the Messenger spacecraft slated to travel to Mercury in the future. (Mercury was the messenger of the gods in mythology.)
  •  Which planet in our solar system is the densest? (Earth)
  •  Which of the 4 terrestrial planets have no moons? (Mercury and Venus)

    • Discussion Topics

  •  What are the main factors that determine the character of a planet? (Answers may vary but should include size, closeness to the Sun, thickness or thinness of its atmosphere.)
  •  How does a greenhouse down here on Earth resemble what astronomers call a planetary "greenhouse effect"? (In a terrestrial greenhouse, glass lets in the Sun's rays, but limits the heat energy escaping from the covered area. For a planet, a thick atmosphere similarly lets in solar energy, but cuts off re-emission.)
  •  Why do you think some astronomers speak of the "Goldilocks Effect" when referring to the temperatures of Venus, Earth and Mars? ("Venus is tooo hot, and Mars is tooo cold, but Earth is juuust right!")

    Hands-on Activities
    LIVE FROM MARS Teacher's Guide, page 14, Activity A.3 Earth / Mars Comparisons
    Approximately 3.8 billion years ago, Mars and Earth are believed to have been very similar. What happened to Mars, and what is our own planet's future? In this Activity, students compare and contrast key characteristics which make Mars similar to and different from Earth. (1-2 class periods)

    LIVE FROM MARS Teacher's Guide, page 43, Activity 3.2 Creating Craters
    Almost all objects in the solar system with solid surfaces have craters. Many of these craters date back to the early days of the solar system. Students work in teams to model cratering and to investigate how mass, velocity, and size of a projectile affect the results of an impact. (1-2 class periods)

    LIVE FROM MARS Teacher's Guide, page 33, Activity 2.2 Reading the Shapes of Volcanoes on Earth and Mars
    How do volcanoes on Earth compare to those on Mars? What processes create their different shapes? Students experiment with various materials to build model volcanoes and compare the slope angles. (1-2 class periods) Add Venus, by using Magellan data via PLANETS.

    LIVE FROM MARS Teacher's Guide, page 49, Activity 5.1 Today's Weather on Mars
    Students research temperature and wind data locally, nationally, and internationally, compare these to conditions on Mars, and draw conclusions about differences and causes. (2-3 class periods) By adding Mercury and Venus to Earth and Mars, you'll have a fun way for students to research the atmosphere, temperature, pressure and other characteristics of the terrestrial planets.

    Online
    BIOgraphies Visit the PTSOLAR website to read more about the research interests and career paths of Chris Chyba and Claudia Alexander. Check out PLANETS for background information (including material to amplify the charts comparing the planets), new discoveries, and links to NASA's past, present and future missions exploring the "4 rocks near the Sun."

    Suggested URLs Messenger Site for the 2004 mission to the least explored of the terrestrial planets, Mercury
    http://sd-www.jhuapl.edu/MESSENGER/

    Venus Earth's twin sister planet was the focus of the very successful and now completed Magellan mission. Great information and images of our "morning star".
    http://www.jpl.nasa.gov/magellan/

    Destination: Earth Official website of NASA's Earth Science Enterprise
    http://www.earth.nasa.gov/

    The Moon NASA Ames Research Center's comprehensive site on the Moon including its history and past NASA missions including the recent Lunar Prospector program.
    http://lunar.arc.nasa.gov/

    Mars Exploration Program: NASA's ongoing series of Mars missions, highlighted by the ongoing Mars Global Surveyor mission. (See online for the latest on 2001 Mars Odyssey)
    http://mars.jpl.nasa.gov/

    Selected "NSES/2061 Benchmarks" met by the video, hands-on and online resources

    1.3.3 Knows the composition and structure of the Earth's atmosphere (e.g., temperature and pressure in different layers of the atmosphere, circulation of air masses)
    1.3.4 Knows ways in which clouds affect weather and climate (e.g., precipitation, reflection of light from the Sun, retention of heat energy emitted from the Earth's surface)
    1.3.6 Knows factors that can impact the Earth's climate (e.g., changes in the composition of the atmosphere; changes in ocean temperature; geological shifts such as meteor impacts, the advance or retreat of glaciers, or a series of volcanic eruptions)
    1.3.7 Knows the processes involved in the water cycle (e.g., evaporation, condensation, precipitation, surface run-off, percolation) and their effects on climatic patterns
    2.2.4 Knows how features on the Earth's surface are constantly changed by a combination of slow and rapid processes (e.g., weathering, erosion, and deposition of sediment caused by waves, wind, water, and ice; sudden changes in the landscape caused by landslides, volcanic eruptions, and earthquakes)
    2.3.4 Knows that the Earth's crust is divided into plates that move at extremely slow rates in response to movements in the mantle
    2.3.5 Knows how land forms are created through a combination of constructive and destructive forces (e.g., constructive forces such as crustal deformation, volcanic eruptions, and deposition of sediment; destructive forces such as weathering and erosion)

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