Understanding What a Galaxy Is
A galaxy is a huge collection of stars, gas, dust, and dark matter held together by gravity. Galaxies come in many shapes and sizes and fill the universe.
What Galaxies Are Made Of
Most galaxies contain billions of stars, along with planets, nebulae, black holes, and massive clouds of gas. Some even have supermassive black holes at their center.
Types of Galaxies
The main shapes are spiral, elliptical, and irregular. The Milky Way, our home galaxy, is a spiral with long arms extending outward from its center.
How Big Galaxies Can Be
Galaxies range from small dwarf galaxies with a few million stars to giants containing trillions. They can span tens to hundreds of thousands of light-years.
Why Galaxies Matter
Galaxies form the large-scale structure of the universe. They create environments where stars are born, evolve, and eventually die in spectacular events.
The Simple Takeaway
A galaxy is a massive group of stars and cosmic material held together by gravity. It is one of the fundamental building blocks of the universe.