Because the moon is tidally locked (meaning the same side always faces Earth), it was not until 1959 that the farside was first imaged by the Soviet Luna 3 spacecraft.

Photograph courtesy NASA/Goddard/Arizona State University

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  • On October 7, 1959, a space probe launched by the Soviet Union, Luna 3, transmitted the first images of the far side of the Moon. Because the moon orbits Earth in a fixed orientation—what astronomers call a synchronous rotation—human beings had only ever seen one side of the Moon.

    Luna 3 took two days to travel to the Moon, where it made several orbits before returning to Earth 207 days later. Luna 3 took 29 photographs, 17 of which were successfully transmitted back to Earth. The images, which covered 70 percent of the Moon’s far side, revealed rugged, mountainous terrain and huge craters, very different from the comparatively smooth side of the moon we can see in the night sky.

  • Term Part of Speech Definition Encyclopedic Entry
    astronomer Noun

    person who studies space and the universe beyond Earth's atmosphere.

    Moon Noun

    Earth's only natural satellite.

    orbit Verb

    to move in a circular pattern around a more massive object.

    Encyclopedic Entry: orbit
    Soviet Union Noun

    (1922-1991) large northern Eurasian nation that had a communist government. Also called the Union of Soviet Socialist Republics, or the USSR.

    space probe Noun

    set of scientific instruments and tools launched from Earth to study the atmosphere and composition of space and other planets, moons, or celestial bodies.