So what is a Black Hole?

by me

A black hole is an astronomical object in space where the gravitational pull is so strong that nothing can escape from it, including light. The “surface” of a black hole is known as the event horizon.

Black holes are undetectable by telescopes because no light can escape from them; However, they can be detected through their interactions with nearby matter. For example, when a star gets too close to a black hole it can be broken apart, and as the gas from the star falls into the black hole, it heats up and emits X-rays and radio waves that can be detected by astronomers. Here’s a visual of how that may look like:

by NASA, ESA, Leah Hustak of STScI

Additionally, the gravitational influence of black holes can affect the orbits of objects around them, which provides further evidence for their presence.

Black holes vary in size, from small (just a few times the mass of the Sun) to supermassive (millions or even billions of times the mass of the Sun). Some of these massive black holes can reside at the centers of galaxies, like our Milky Way.

More on black holes can be read by clicking here.