There are a lot of stars. Stars are made of of a luminous spheroid of plasma held together by its own gravity.

Space exploration was drives by the fear of nuclear fallout and this made people explore space to find more shelter or resources. Then it turned into a race between the USA AND USSR. The USSR won most of the rounds with sending the first person into space, the first rocket to orbit the earth and to take pictures and more but the US had its first big victory in 1969, when they sent the first man to the moon.

I know that black holes come from really big stars that collapse on themselves when they die. Dying stars can either become black holes or black dwarves.

Our neighboring galaxy is Andromeda, which is about double the size of the Milky way

The universe started as being very tiny and very, very compact then the big bang happened 13.8 billion years ago and its still expanding which means the universe has still not stopped expanding

All planets in the known universe are in orbit of a star, sometimes there's more than one like the solar system. Without a star in the middle of something like the solar system, all the planets would obviously freeze and probably be too cold for any like forms but it there was a star with no gravitational pull(this is super hypothetical, that's clearly not possible) but all the planets would get out of orbit and probably collide or do something much worse. With no gravitational pull, any and all planets would just drift around, with unpredictable movements that will probably crash into something

Parsecs and light years are a measure of distance, not time

There are approx. 400 planets that could have life in the known universe

Space is completely silent. There is no oxygen or other gas in space, which means that sound has no way to travel because sound travels in waves through oxygen

Gravity works when a large mass that is usually a sphere attracts other things to its surface. This happens everywhere and once a smaller object get in a specific radius, that object is caught in orbit. If an object bigger than another one, they collide because the gravitational pull of the bigger object is too big. This principle works all over the known universe because all the galaxies we know are held together by a black hole. Black holes have an exceptional gravitational pull, which is how the whole galaxy stays together. So if you are on space, you can drift anywhere but if you get too close to a big object, you would be pulled towards the surface of that object.