event horizon

noun

Definition of event horizon

: the surface of a black hole : the boundary of a black hole beyond which nothing can escape from within it

Examples of event horizon in a Sentence

Recent Examples on the Web The time between the steady pulsating of this black hole can tell astronomers about the size and structure of the matter nearest to the black hole's event horizon--that's the area where not even light can escape the black hole's gravitational pull. Ashley Strickland, CNN, "Astronomers witness the steadfast beating heart of a black hole," 12 June 2020 By charting how those x-rays behave, scientists created an extremely detailed map of the region around the black hole’s event horizon, the zone beyond which not even light can escape. National Geographic, "Astronomers just got a deep peek at a black hole," 20 Jan. 2020 From those many hours’ worth of data, Alston and his colleagues assembled a map of the supermassive black hole’s x-ray corona and its accretion disk, a ring of swirling matter that’s just outside the event horizon. National Geographic, "Astronomers just got a deep peek at a black hole," 20 Jan. 2020 Here, our people are met with a bureaucratic black hole, beyond which event horizon no answer returns. al, "The truth will tell itself," 12 Mar. 2020 Around larger black holes, tidal disruption doesn’t happen until a star or planet is inside the event horizon, so anything outside is safe from that fate. Daniel Clery, Science | AAAS, "Could a habitable planet orbit a black hole?," 4 Feb. 2020 In order to receive strong enough CMB light, a planet would need to orbit very close to the black hole’s event horizon. Daniel Clery, Science | AAAS, "Could a habitable planet orbit a black hole?," 4 Feb. 2020 The deep blackness of the event horizon, looming over nearly half the sky, would be a forbidding presence. Daniel Clery, Science | AAAS, "Could a habitable planet orbit a black hole?," 4 Feb. 2020 After spaghettification, whatever entered the black hole—stars, dust, planets, or unfortunate astronauts—has crossed an invisible barrier called the event horizon, or the point of no return. Maria Paula Rubiano, Popular Science, "What would happen if you fell into a black hole?," 2 Jan. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'event horizon.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of event horizon

1956, in the meaning defined above

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The first known use of event horizon was in 1956

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Last Updated

18 Jun 2020

Cite this Entry

“Event horizon.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/event%20horizon. Accessed 15 Jul. 2020.

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