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    On December 7, 1972, NASA astronauts took a parting shot as they left “parking orbit” around Earth and continued on their mission to the Moon. The Apollo 17 crew snapped a photograph of our planet that became one of the most iconic and familiar in all of human history, an image nicknamed the “Blue Marble.”
    Apollo 17 was the last manned mission to the Moon—no one has ever again been far enough away from Earth to take a similar image. Satellite imagery, however, has documented our planet in even greater detail, from the change in seasons, cloud cover, and even the display of man-made “lights at night.” 
    The unique “Blue Marble” image was possible due to the orientation of the astronauts as they left “parking orbit.” The sun was at their backs, allowing an entire hemisphere to be illuminated. The December solstice was quickly approaching, which put the Northern Hemisphere mostly out-of-frame and made large sections of Antarctica visible
  • Term Part of Speech Definition Encyclopedic Entry
    astronaut Noun

    person who takes part in space flights.

    cloud Noun

    visible mass of tiny water droplets or ice crystals in Earth's atmosphere.

    Encyclopedic Entry: cloud
    cloud cover Noun

    amount of sky covered with clouds.

    display Verb

    to show or reveal.

    document Verb

    to keep track of.

    hemisphere Noun

    half of a sphere, or ball-shaped object.

    Encyclopedic Entry: hemisphere
    iconic Adjective

    event or symbol representing a belief, nation, or community.

    illuminate Verb

    to shine light on.

    island Noun

    body of land surrounded by water.

    Encyclopedic Entry: island
    man-made Noun

    produced by people.

    manned Adjective

    carrying one or more people.

    mission Noun

    important goal or purpose.

    Moon Noun

    Earth's only natural satellite.

    NASA Noun

    (National Aeronautics and Space Administration) the U.S. space agency, whose mission statement is "To reach for new heights and reveal the unknown so that what we do and learn will benefit all humankind."

    Northern Hemisphere Noun

    half of the Earth between the North Pole and the Equator.

    ocean Noun

    large body of salt water that covers most of the Earth.

    Encyclopedic Entry: ocean
    orientation Noun

    an object or person's position in relation to true north.

    parking orbit Noun


    temporary orbit reached as a launch vehicle boosts a satellite, where it coasts in parking orbit for a while, then fires again to push the vehicle into the final desired trajectory.

    peninsula Noun

    piece of land jutting into a body of water.

    Encyclopedic Entry: peninsula
    planet Noun

    large, spherical celestial body that regularly rotates around a star.

    Encyclopedic Entry: planet
    rain forest Noun

    area of tall, mostly evergreen trees and a high amount of rainfall.

    Encyclopedic Entry: Rain forest
    Sahara Desert Noun

    world's largest desert, in north Africa.

    satellite imagery Noun

    photographs of a planet taken by or from a satellite.

    season Noun

    period of the year distinguished by special climatic conditions.

    Encyclopedic Entry: season
    similar Adjective

    alike or resembling.

    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
    visible Adjective

    able to be seen.