How Many Black Holes Are There?

Astronomers have found about 2.5 million active black holes using the Wide-field Infrared Survey Explorer (WISE) telescope. Some of these black holes are as far as 10 billion light years away from Earth. This count, however, reflects only the black holes that are actually visible from Earth.

More about black holes:

  • Most stars, including Earth's sun, will never end up as black holes — they are simply too small to exert the necessary gravitational pull and will end up as neutron stars or white dwarfs.

  • There is no standardized system for assigning names to black holes. The names of black holes might be related to the people who discovered them, the telescopes that were used in their discovery or the constellations to which they belong.

  • As of 2012, the largest known black hole was M87. This black hole has a diameter of about 25 billion miles (40 billion km). This is 6.6 billion times the mass of Earth's sun. Earth's diameter, by comparison, is a little less than 8,000 miles (12,756 km).

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