What is the Universe Made of? 

This is one of those questions that has an answer that is quite mind-expanding. Basically, the universe consists of galaxies and the objects they contain: stars, planets, nebulae, black holes and other dense objects. The early universe was largely hydrogen with some helium and lithium, and the first stars formed from that helium. As they evolved and died, they created heavier and heavier elements, which formed second- and third-generation stars and their planets.