• A NASA satellite instrument, CERES, took these images in 2004 and 2005. The images are measurements of the Earth’s albedo—the amount of solar radiation reflected from Earth back into space. 
     
    The CERES images show a radical difference in albedo between the Northern and Southern Hemispheres, as well as between the December and June solstices. The Southern Hemisphere reflects a tremendous amount of radiation during the December solstice (top image), while the Northern Hemisphere reflects more radiation in June.
     
    Instructional Ideas
     
    Consult National Geography Standard 7.2 (4th grade): The physical processes that shape the patterns of Earth's surface. Earth-Sun relationships affect conditions on Earth.
    Discuss the relationship between the position of the Earth in its orbit around the sun and changes experienced on Earth:
    • temperature
    • light
    • different impacts of solar radiation on land and water
     
    Questions in the "Questions" tab explore some ways solar radiation differs in the Northern and Southern Hemispheres on the solstices.
    • Solar radiation measured by CERES includes not just the visible spectrum of light, but ultraviolet and infrared—wavelengths too short (ultraviolet) or too long (infrared) for the human eye to see. 
    • Clouds do most of the reflecting in these NASA images. (In fact, CERES, the instrument responsible for these images, stands for Clouds and Earth’s Radiant Energy System.)

    • According to CERES, the amount of solar energy received at the North Pole is 30% higher during the summer solstice than the amount of solar energy received at the Equator.

    • Scientists measure solar radiation in Watts per square meter (W/m2). Calculating this measurement involves some pretty sophisticated—but pretty reliable—math. Check it out here.
  • Term Part of Speech Definition Encyclopedic Entry
    albedo Noun

    scientific measurement of the amount of sunlight that is reflected by a surface.

    hemisphere Noun

    half of a sphere, or ball-shaped object.

    Encyclopedic Entry: hemisphere
    measurement Noun

    process of determining length, width, mass (weight), volume, distance or some other quality or size.

    NASA Noun

    (acronym for National Aeronautics and Space Administration) U.S. agency responsible for space research and systems.

    reflect Verb

    to rebound or return light from a surface.

    satellite Noun

    object that orbits around something else. Satellites can be natural, like moons, or made by people.

    season Noun

    period of the year distinguished by special climatic conditions.

    Encyclopedic Entry: season
    solar radiation Noun

    light and heat from the sun.

    solstice Noun

    astronomical event that occurs twice a year, when the sun appears directly overhead to observers at the Tropic of Cancer or the Tropic of Capricorn.

    Encyclopedic Entry: solstice
    sunlight Noun

    visible radiation from the sun.

    tremendous Adjective

    very large or important.

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