system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Supernovae, Neutron stars, and black holes.

What causes each one to happen, How are each possible, and different from each other? It seems like they all occur due to gravity, but how doesn't a neutron star form a black hole?
gpt
* **Supernova**: when a massive star blows up, initiated by the sudden (takes less than a second) collapse of it's core.  The collapse of the core is initiated when the pressure from nuclear fusion can no longer hold up against the immense gravity pushing in.  There are generally two types, Ia and II.
* **Neutron Star**: a super-massive and super-dense star where all the space between the the neutrons and electrons of the atoms of the star has been eliminated.  In other words, the atoms have been crushed so there is virtually no space between the neutrons and electrons.  A teaspoon of neutron star would weight millions and millions of pounds.
* **Black holes**: when a super-massive star's core collapses all the way down to a singularity, an infinitely dense and infinitely small point.  Bends space-time so much that not even light can escape it's gravitational pull.  If you get close enough (called the event-horizon), you will never be able to escape the black hole's pull.