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Do you know what a black hole is? Do they really exist? Black holes have fascinated people’s imaginations for decades and have inspired many stories and movies.

Simply put, a black hole is the last phase in a massive star’s life cycle. But to better understand this concept, you need to know about the life of a star.

Stars are large hot bodies of hydrogen gas that burn brightly for millions or even billions of years through nuclear fusion. Not all stars are the same size. The size of a star is determined by its mass, which is the amount of gas that the star is made of, and therefore will burn in its lifetime. The sun in the center of our solar system is a star. We can use the mass of our sun as a way to measure the mass of other stars in relation to it. For example our sun is 1 solar mass, and a star twice as big as the sun is 2 solar masses. Now hold on to your hats because this is where things can get tricky.

All stars, large and small, form the same way and eventually begin to burn gas through fusion, creating light. Smaller stars burn through gas slower than larger stars. This means that large stars do not live as long as small stars, even though small stars are made of less gas. When a small star is done burning, the temperature of the star cools and the light dims. Eventually the small star does not shine anymore and becomes what is called a “black dwarf.”

When a very large star, at least 3 times the size of our sun (3 solar masses), is done burning it leaves behind an iron core with such a great mass that the core itself contracts and becomes a black hole. The mass at the center of the black hole is so great and so dense that its gravity does not let anything escape the black hole. Not even light can escape a black hole.

If you were being swallowed by a black hole, you would have to travel faster than the speed of light just to have a chance of escaping the black hole’s gravitational pull.