1. Black Holes

2. Basic Information
Black holes are very complex and one of the biggest mysteries to humankind.
What we do know:
Black holes are stars that have collapsed.
Black holes are objects in space with so much gravity, it sucks even itself inward.
Nothing can escape the gravitational force of a black hole, not even light.

3. Formation
To be large enough for a star to collapse, it must be at least five to ten times the size of our sun.
When a star’s hydrogen has been converted to helium, nuclear fusion can no longer counterbalance its gravity
Due to how dense the core becomes with helium (larger than hydrogen) and the lack of nuclear fusion, the gravitational pull is too strong and the star gets sucked inward.
The force is so strong not even light can escape its pull, hence black holes are dark and invisible.

4. Supermassive Black Holes
Supermassive black holes are at the center of almost every galaxy.
These are black holes with the mass of around one million times that of our sun but can fit into about the diameter of our solar system.
The gravity of these behemoths is what keeps galaxies together.
The one at the center of our galaxy is Sagittarius, it is about the mass of four million suns and fits into about the diameter of the sun.

6. Event Horizon
The name for the outer edge, or limit, of the black hole.
Outside of this perimeter, it is still possible to escape, but once anything crosses over the event horizon, it can no longer escape the gravitational pull of the black hole, not even light.
In order to be able to escape the pull of the black hole within the event horizon, an object would need to be moving at a speed faster than that of the speed of light. As of yet, we do not know of anything capable of moving beyond this speed, so to our current knowledge, nothing can escape the pull of a black hole’s gravity.

7. Inside of a Black Hole
So much controversy and confusion surrounds what actually happens when something enters a black hole.
We know that radiation is being shot out of black holes and we know that there is a point called the “event horizon” where space and time is no longer how we know.
However, there are many theories about what happens upon entering one.
One of the newest (that I could find) is one theorized by a professor at Ohio State who claims that a black hole is like a copy machine.
He believes that when a three-dimensional object enters, it is compressed into a two- dimensional hologram of itself.

8. More Recent Studies
Black holes are one of the topics that most quickly changes and updates its information due to new findings.
We know so little about them, so the more we study, the more progress we make in finding out the truth behind such a mysterious subject.
The Milky Way’s black hole has shown signs of increased activity
A light signal has appeared from two colliding black holes
Hubble has found evidence of a galaxy star birth regulated by a black hole fountain

9. Why do black holes exist/occur?
Can our sun become a black hole?
Can you see a black hole? Why/why not?
What is (or what do you think is) past the event horizon of a black hole?
What is the difference between supermassive and regular black holes?