Medium-sized stars, like our Sun, do not become black holes. They end their lives as white dwarfs.

Here's why:

* Black holes form from the collapse of very massive stars. Stars much larger than our Sun (at least 8 times the mass of the Sun) have enough gravity to overcome the outward pressure of their nuclear fusion.

* When these massive stars run out of fuel, their core collapses inward. This collapse is so violent that it creates a black hole, a region of spacetime where gravity is so strong that nothing, not even light, can escape.

* Medium-sized stars like our Sun are not massive enough. They don't have the gravitational force needed to create the extreme conditions necessary for a black hole.

Instead, when medium-sized stars reach the end of their lives, they shed their outer layers, leaving behind a dense, hot core called a white dwarf.