What is a black hole?
A black hole is what remains of a red giant that burnt out its fuel, collapsed by its own gravity. If the star collapsed not too fiercely, the star will become a nebula, which likes emitting electromagnetic rays but is almost completely harmless. If the star had crushed fiercely, it would've formed a black hole. Black holes are an area of space which has intense gravity. Black holes are invisible, due to the fact that no light can escape from them. If you were to stand inside a black hole(not saying that it is actually physically possible) and shone a flashlight at the mouth of the black hole, the light would curve back, due to the fact that no light can escape from a black hole. The diagram to the left is a black hole. The ring singularity is the absolute heart of the black hole. It is where all of the objects and light that a black hole attracts goes.
What is the event horizon?
The event horizon is the edge of the black hole from where light can or cannot escape. For example, imagine the black hole as a bathtub. The entire bathtub represents the area around the black hole. The sinkhole is the black hole. There is a certain range where the sinkhole will affect the matter around it, like a black hole. At a certain distance from the black hole, light can escape with no problem at all. Let's say light is a toy boat. If the boat is too close to the plughole, the boat will be sucked in, like light. However, if the boat is halfway between the plughole and the rest of the bathtub, it would remain still, as the gravity of the black hole and the gravity of space compete against each other in a cosmic tug-of-war.
How can a Black Hole destroy our planet?
Black holes are dangerous, and like you read above, suck in things. They would do the same to our planet if we got too close to it or it got too close to us. It will basically suck our planet in. The black hole would probably rip us apart first into tiny, bite-sized chunks, or just suck us in. No one knows what lies in a black hole because no one has been suicidal or gullible enough to jump in. So the ripping apart or the lack of heat to help us against the freezing cold of space will still destroy us. Pretty simple, huh? Not much to describe at all.
Don't Black holes go around sucking up everything in sight?
Actually, no. Black holes don’t go about sucking everything up or else the entire universe would’ve been sucked up by now. Most black holes are dormant, meaning that they don’t or haven’t sucked up anything in ages. A dormant black hole is at the centre of our galaxy. It doesn’t swallow much, which is very good news for us. However, active black holes are the ones that suck stuff up. In these black holes, they usually stay in a general position, so yeah, they can’t really go sucking us up. The only real danger is if a new black hole formed near us.
Likelihood
Hmmm… The likelihood of a black hole sucking us up. Not very much. First of all, if a star close and big enough to create a black hole close to us did create a supernova, we would probably die of the supernova or the radiation. And if our Sun did it, we would be dead anyway. So the likelihood of a black hole being actually getting the chance to kill us is:
0.25/10
0.25/10
