The hydrogen bomb that exploded as part of a test codenamed "Castle Bravo" was the largest nuclear device ever detonated by the United States.

Photograph courtesy U.S. Department of Energy

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  • On March 1, 1954, a U.S. Navy plane dropped a hydrogen bomb on the Bikini Atoll, part of the Marshall Islands. Code-named “Castle Bravo,” the 15-megaton bomb—a thousand times more powerful than the atomic bomb dropped on Hiroshima, Japan—remains the most powerful nuclear weapon ever detonated by the United States. 
    Before testing began, the 167 Marshallese people who lived on Bikini were relocated to other islands. The U.S. military used the Marshall Islands to test nuclear weapons from 1946 to 1958.
    Today, a handful of caretakers live on Bikini. Most do field work for the U.S. government, including sampling the soil, plants, water, and marine life around the island. Many people from the Bikini Atoll are still hoping to return to their homeland, although tests indicate that the amount of radiation present in the island's food web could be harmful to them. The type of radiation detected at Bikini (cesium-137) has been linked to an increased risk for several types of cancer.
  • Term Part of Speech Definition Encyclopedic Entry
    atomic bomb Noun

    explosive device that draws energy from the interaction of atomic nuclei. Also called an atom bomb, a-bomb, or nuclear bomb.

    Bikini Atoll Noun

    ring of 23 coral islands in the South Pacific Ocean, part of the Marshall Islands, where the U.S. carried out nuclear tests from 1946-1958.

    cancer Noun

    growth of abnormal cells in the body.

    detonate Verb

    to cause something to explode.

    field work Noun

    scientific studies done outside of a lab, classroom, or office.

    Encyclopedic Entry: field work
    food web Noun

    all related food chains in an ecosystem. Also called a food cycle.

    Encyclopedic Entry: food web
    government Noun

    system or order of a nation, state, or other political unit.

    hydrogen bomb Noun

    powerful explosive that uses the energy from the fusion of hydrogen isotopes. Also called an h-bomb, fusion bomb, or thermonuclear bomb.

    indicate Verb

    to display or show.

    marine Adjective

    having to do with the ocean.

    military Noun

    armed forces.

    nuclear weapon Noun

    explosive device that draws power from the splitting and combining of atomic nuclei.

    radiation Noun

    energy, emitted as waves or particles, radiating outward from a source.

    relocate Verb

    to move a residence or business from one place to another.

    soil Noun

    top layer of the Earth's surface where plants can grow.

    U.S. Navy Noun

    military branch whose mission is "to maintain, train, and equip combat ready Naval forces capable of winning wars, deterring aggression, and maintaining freedom of the seas."