A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. [1][2] The word is derived from the Greek galaxias (γαλαξίας), literally …

Feb 6, 2026 · Galaxies consist of stars, planets, and vast clouds of gas and dust, all bound together by gravity. The largest contain trillions of stars and can be more than a million light …

Jan 25, 2026 · The existence of galaxies was not recognized until the early 20th century. Since then, however, galaxies have become one of the focal points of astronomical investigation. …

Feb 5, 2026 · Discover what a galaxy is explained in simple terms, how many galaxies exist, and how the universe size shapes our view of the cosmos—packed with clear, engaging science.

Explore our cosmic neighborhood in an interactive 3D map featuring the Milky Way, Andromeda, Triangulum, and dozens of nearby dwarf galaxies. Built for curious learners, stargazers, and …

With more than 100 billion galaxies in the observable universe, the exciting discoveries and unanswered questions are endless. Each one is unique, from ellipticals that have quenched …

Mar 19, 2025 · Galaxies are the grand islands of the universe, each one a vast metropolis of stars, gas, dust, dark matter, and endless possibility. From tiny dwarfs to sprawling giants, …

Astronomy.com is for anyone who wants to learn more about astronomy and space, including planets, galaxies, asteroids, and NASA.

Jan 18, 2024 · Galaxies are among the largest and most beautiful objects in the night sky. These huge swirling masses are where almost every star in the Universe is born, lives and dies.

This page explains that galaxies are vast systems made up of stars, remnants, interstellar medium, and dark matter, named after the Greek word for milk. There are approximately 170 …