The sun sends out particles that dance in our atmosphere, painting the sky with magical glows, far from warmth. What am I?

I am the smallest building block of everything that exists, yet I have a nucleus and clouds around me. Solve the riddle → With a hidden force, I guide travelers across the world's oceans, always pointing towards an invisible pole that rarely rests. Solve the riddle → You build it slowly with words, but it crumbles quickly with a single one. Solve the riddle → What navigates in total darkness using sound waves but doesn't have radar? Solve the riddle → Your internal army fights invisible invaders, without your command, day and night. Solve the riddle →