A bit silly, but also profound; what it takes to make your own habitable world.
Go to
http://astroventure.arc.nasa.gov/
Yes! That NASA site is a little silly and immature, but
it can teach you some profound scientific and philosophical truths.
IOW, Would you like to know how extremely narrow the physical/environmental parameters.
are that allow you to EXIST as walking, talking breathing thing that you are? ;-)