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What is the Diameter of a Black Hole?

-- Ray | May 8, 2024

Question:

What is the estimated diameter in meters of the black hole at the center of the Milky Way? I am interested in the actual diameter of the black hole, not of the event horizon.
How reliable do you believe your answer to be?

-- Ray

Answer:

In fact, the diameter of a black hole is defined by its event horizon, as a black hole’s entire mass is concentrated in an almost infinitely small and dense point called a singularity. The event horizon is the distance from the black hole singularity at which the escape velocity from the black hole exceeds the speed of light. You can find a nice encyclopedia of black holes, including their properties, in the Black Hole Directory. This directory lists the black hole at the center of the Milky Way as having a diameter of roughly 15 million miles, or 24 million km.

-- Jeff Mangum

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