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  1. Galaxy - Wikipedia

    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 'milky', a reference to …

  2. Galaxies - NASA Science

    May 2, 2025 · 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-years across. The …

  3. Galaxies—facts and information | National Geographic

    Galaxies are sprawling systems of dust, gas, dark matter, and anywhere from a million to a trillion stars that are held together by gravity. Nearly all large galaxies are thought to also...

  4. Galaxy - ESA/Hubble

    Galaxies are collections of stars, dust, gas, and dark matter, which are bound together by the gravitational attraction that results from their own mass. A small dwarf galaxy contains a few million …

  5. Galaxies: Collisions, Types and How They're Made | Space

    Jan 4, 2019 · Galaxies are composed of stars, dust and dark matter, all held together by gravity. Astronomers aren't certain exactly how galaxies formed. After the Big Bang, space was made up …

  6. What is a galaxy? - Live Science

    Aug 25, 2021 · Galaxies are groups of stars and other space objects held together by gravity. There are more than 100 billion galaxies in the universe, each presenting beautiful structures that can be seen in...

  7. What Is a Galaxy? | NASA Space Place – NASA Science for Kids

    Sep 25, 2025 · What Is a Galaxy? The Short Answer: A galaxy is a huge collection of gas, dust, and billions of stars and their solar systems, all held together by gravity. We live on a planet called Earth …

  8. Milky Way Galaxy | Size, Definition, & Facts | Britannica

    Dec 7, 2025 · Milky Way Galaxy, large spiral system consisting of several hundred billion stars, one of which is the Sun. It takes its name from the Milky Way, the irregular luminous band of stars and gas …

  9. Elliptical galaxy - Wikipedia

    The largest elliptical galaxy IC 1101 An elliptical galaxy is a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the three main classes of …

  10. How galaxies form: Theories, variants and growth | Space

    Jul 13, 2022 · Here are some of the most promising theories of how galaxies form, how and why they merge, as well as the different varieties of galaxies that have been observed. As the universe …