More than 80 million trees were felled by the shock wave from a meteor that exploded over Siberia in 1908. More than 20 years later, a photographer on a Russian science expedition recorded the devastated landscape of the "Tunguska Event."
Photograph by Evgeny Leonidovich Krinov, courtesy Wikimedia

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    On June 30, 1908, a meteor exploded near the remote Podkamennaya Tunguska River in Siberia, Russia. As of 2014, the Tunguska Event is the largest “impact event” in recorded history.
    Astronomers and meteorologists have studied the Tunguska Event using mathematical models, expeditions to Siberia, eyewitness accounts, and sediment cores from peat bogs in the Tunguska region. Using these resources, scientists have a pretty good idea about what happened during the Tunguska Event.
    A 100-million kilogram (220 million-pound) space rock crashed through Earth’s atmosphere at about 54,000 kilometers per hour (33,500 miles per hour). As it sped through the atmosphere, the rock heated to a scorching 25,000 degrees Celsius (44,500 degrees Fahrenheit). About 6-10 kilometers (4-6 miles) above the Tunguska region, the rock exploded. The enormous explosion immediately felled 80 million trees, and caused a shock wave that shook houses 65 kilometers (40 miles) away.
    So, although the Tunguska Event is usually classified as an “impact,” the meteor actually exploded before it ever hit the ground.
  • Term Part of Speech Definition Encyclopedic Entry
    astronomer Noun

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

    atmosphere Noun

    layers of gases surrounding a planet or other celestial body.

    Encyclopedic Entry: atmosphere
    bog Noun

    wetland of soft ground mostly made of partially decayed plant matter called peat.

    Encyclopedic Entry: bog
    damage Noun

    harm that reduces usefulness or value.

    enormous Adjective

    very large.

    expedition Noun

    journey with a specific purpose, such as exploration.

    explosion Noun

    violent outburst; rejection, usually of gases or fuel

    forest Noun

    ecosystem filled with trees and underbrush.

    meteor Noun

    rocky debris from space that enters Earth's atmosphere. Also called a shooting star or falling star.

    Encyclopedic Entry: meteor
    meteorologist Noun

    person who studies patterns and changes in Earth's atmosphere.

    model, computational Noun

    a mathematical model that requires extensive computational resources to study the behavior of a complex system by computer simulation.

    peat Noun

    layers of partially decayed organic material found in some wetlands. Peat can be dried and burned as fuel.

    region Noun

    any area on Earth with one or more common characteristics. Regions are the basic units of geography.

    Encyclopedic Entry: region
    remote Adjective

    distant or far away.

    scorching Adjective

    very hot.

    sediment core Noun

    cylinder of accumulated sediment of a region, visible as layers.

    shock wave Noun

    moving, measurable change in pressure and density of a material.