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Fact sheet: Black hole

This is the first real image of a black hole ever captured. (Credit: Event Horizon Telescope Collaboration)


A black hole is a region of space having a gravitational field so intense that no matter or radiation can escape. A black hole is created after the death of a very massive star. The core of the star collapses in on itself, causing a supernova – a massive explosion of the star's outer layers. All of the former star's matter is then concentrated into a single tiny point (known as a singularity). The gravity of a black hole is so strong that nothing – not even light – can escape its pull.

Black holes are generally categorized according to the mass they contain. There are three main types:

Scientists are still not sure how supermassive black holes are created, although they may be formed through mergers of smaller, stellar black holes.

In this video, learn more about black holes with Sarah Gallagher, astrophysicist and Science Advisor to the President of the Canadian Space Agency (CSA). (Credit: CSA)



A black hole's singularity is an infinitely tiny point in its innermost region. The boundary surrounding a black hole, known as the event horizon, varies in size.


Black holes vary in mass. They can range from 10 times to several billion times the mass of our Sun.


The more massive a black hole, the colder it is.

Stellar black holes are very cold: they have a temperature of nearly absolute zero – which is zero Kelvin, or −273.15 degrees Celsius.

Supermassive black holes are even colder.

But a black hole's event horizon is incredibly hot. The gas being pulled rapidly into a black hole can reach millions of degrees.



Because black holes are formed at the end of a large star's life, black holes are scattered throughout galaxies. Supermassive black holes are found at the centre of most galaxies, including our own galaxy, the Milky Way.

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