The document discusses key facts about cosmology and the structure of the universe, galaxies, stars, and the solar system. It provides details on:
- The universe consists of millions of galaxies held together by gravity, with galaxies flying away from each other as the universe expands.
- Our galaxy, the Milky Way galaxy, is spiral in shape and contains over 100 billion stars revolving around its center.
- The widely accepted Big Bang theory is that 15 billion years ago, the universe was in an extremely dense state and began rapidly expanding.