Publish date:
Updated on
Year
1956

United States drops hydrogen bomb over Bikini Atoll

The United States conducts the first airborne test of an improved hydrogen bomb, dropping it from a plane over the tiny island of Namu in the Bikini Atoll in the Pacific Ocean. The successful test indicated that hydrogen bombs were viable airborne weapons and that the arms race had taken another giant leap forward.

The United States first detonated a hydrogen bomb in 1952 in the Marshall Islands, also in the Pacific. However, that bomb–and the others used in tests that followed–were large and unwieldy affairs that were exploded from the ground. The practical application of dropping the weapon over an enemy had been a mere theoretical possibility until the successful test in May 1956. The hydrogen bomb dropped over Bikini Atoll was carried by a B-52 bomber and released at an altitude of more than 50,000 feet. The device exploded at about 15,000 feet. This bomb was far more powerful than those previously tested and was estimated to be 15 megatons or larger (one megaton is roughly equivalent to 1 million tons of TNT). Observers said that the fireball caused by the explosion measured at least four miles in diameter and was brighter than the light from 500 suns.

The successful U.S. test meant that the ante in the nuclear arms race had been dramatically upped. The Soviets had tested their own hydrogen bomb in 1953, shortly after the first U.S. test in 1952. In November 1955, the Soviets had dropped a hydrogen bomb from an airplane in remote Siberia. Though much smaller and far less powerful (estimated at about 1.6 megatons) than the U.S. bomb dropped over Bikini, the Russian success spurred the Americans to rush ahead with the Bikini test.

The massive open-air blast in 1956 caused concerns among scientists and environmentalists about the effects of such testing on human and animal life. During the coming years, a growing movement in the United States and elsewhere began to push for a ban on open-air atomic testing. The Limited Test Ban Treaty, signed in 1963 by the United States, the Soviet Union, and Great Britain, prohibited open-air and underwater nuclear testing.

FACT CHECK: We strive for accuracy and fairness. But if you see something that doesn't look right, click here to contact us!

ALSO ON THIS DAY

Vasco da Gama reaches India

Portuguese explorer Vasco de Gama becomes the first European to reach India via the Atlantic Ocean when he arrives at Calicut on the Malabar Coast. Da Gama sailed from Lisbon, Portugal, in July 1497, rounded the Cape of Good Hope, and anchored at Malindi on the east coast of ...read more

Christopher Columbus dies

On May 20, 1506, the great Italian explorer Christopher Columbus dies in Valladolid, Spain. Columbus was the first European to explore the Americas since the Vikings set up colonies in Greenland and Newfoundland in the 10th century. He explored the West Indies, South America, and ...read more

Lincoln signs Homestead Act

On this day in 1862, President Abraham Lincoln signs the Homestead Act, which opens government-owned land to small family farmers (“homesteaders”). The act gave “any person” who was the head of a family 160 acres to try his hand at farming for five years. The individual had to be ...read more

Frank Sinatra is laid to rest

Long before his stature in the world of show business earned him the nickname “Chairman of the Board,” Frank Sinatra was known simply as “The Voice.” During a career that saw him go from skinny teen idol to middle-aged playboy, Sinatra’s personality and looks were certainly major ...read more

"The Simpsons" airs 400th episode

On this day in 2007, Fox’s long-running animated series The Simpsons airs its 400th episode. The Simpsons was created by Matt Groenig, whose comic strip Life Is Hell caught the attention of the Hollywood producer James L. Brooks. Brooks enlisted Groenig to create a cartoon short ...read more