This document discusses the origin and evolution of galaxies, stars, and planets in the universe. It describes how the universe began in a hot dense state 13.8 billion years ago and has expanded and cooled since then. Within the first few hundred million years, the first proto-galaxies formed from dense clouds of hydrogen and helium gas. These proto-galaxies eventually hosted the earliest giant stars, some hundreds to thousands of times more massive than the Sun. These short-lived early stars played a key role in producing heavier elements through supernova explosions, seeding the universe for future star and planet formation.
This document discusses the origin and evolution of galaxies, stars, and planets in the universe. It describes how the universe began in a hot dense state 13.8 billion years ago and has expanded and cooled since then. Within the first few hundred million years, the first proto-galaxies formed from dense clouds of hydrogen and helium gas. These proto-galaxies eventually hosted the earliest giant stars, some hundreds to thousands of times more massive than the Sun. These short-lived early stars played a key role in producing heavier elements through supernova explosions, seeding the universe for future star and planet formation.
