Yes, you are depressed. (((hugs)))

Firefighters and police don't think life is pointless because they are out there knowing the make a difference in many lives each day.

Thinking alot is a symptom of depression. Tell us what kinds of things you do to distract yourself from thinking. Distraction is good, even if it's computer games or movies, photography etc. Even when you don't feel quite up to anything, by pushing yourself a bit and doing you will begin to feel some better.

BTW I don't believe any of that about the sun and the solar system.