Black holes primarily form through the gravitational collapse of very massive stars at the end of their life cycles. When a star with a mass roughly 8 to 10 times or more that of the Sun exhausts its nuclear fuel, it can no longer support itself against gravity. The core collapses, and this collapse can trigger a supernova explosion that blows away the star's outer layers. What remains is a stellar-mass black hole, a compact object with mass a few times that of the Sun
. There are two main types of black holes based on formation:
- Stellar-mass black holes: Formed from the collapse of massive stars after supernova explosions. These black holes typically have masses a few times that of the Sun
- Supermassive black holes: Found at the centers of most galaxies, they are millions to billions of times more massive than the Sun. Their formation is less well understood but may involve the direct collapse of massive gas clouds in the early universe, growth by accreting matter, and mergers of smaller black holes over billions of years
Additionally, some black holes may form from the direct collapse of gas clouds without first forming stars, producing more massive black holes early in the universe's history. These could serve as seeds for supermassive black holes
. In summary, black holes form when gravity overwhelms all other forces in massive objects, causing them to collapse into an extremely dense point with a gravitational field so strong that not even light can escape
