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Astronomy & Space vocabulary · Stars & Stellar Evolution

Event horizon

Meaning in astronomy & space, with examples

nounAdvanced term

In astronomy & space, event horizon means: The boundary around a black hole beyond which nothing, not even light, can escape. Anything that crosses it can never come back out.

In Turkish: olay ufku

How it is used

Used in astrophysics and in popular science about black holes. Its size depends on the black hole's mass. The Event Horizon Telescope, a worldwide network of radio dishes, is named after it.

Example sentences

  1. Once matter crosses the event horizon, it is lost from our view forever.

  2. The event horizon of a black hole with the Sun's mass would have a radius of only about three kilometres.

Common collocations

  • cross the event horizon
  • beyond the event horizon
  • size of the event horizon
  • black holeA region of space where matter is packed so tightly that gravity stops anything, even light, from escaping. Many form when very massive stars collapse.
  • supermassive black holeA black hole with the mass of millions or billions of Suns. Almost every large galaxy, including the Milky Way, has one at its centre.
  • gravityThe force that pulls any two objects with mass towards each other. It keeps the planets in orbit around the Sun and keeps our feet on the ground.
  • escape velocityThe minimum speed an object needs to break free from the gravity of a planet or another body without any further push. For Earth it is about 11.2 km per second.

More terms: Stars & Stellar Evolution

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