Answer:
I am a type of weapon for SCI-FI characters
I go through a door but never go in and never come out.
I always follow you around, everywhere you go at night. I look very bright to people, but I can make the sun dark. What am I?
I am clean when Iām black dirty when Iām white.
You used to come to me for all sorts of information and knowledge before the internet was born
As round as an apple. As deep as a cup. All the king's horses can't pull it up.