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 the Milky Way galaxy that contains the Solar System.

2024年10月22日 · 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 smallest can contain a few thousand stars and span just a few hundred light-years.

2024年7月27日 · Our galaxy, the Milky Way, sits in a Local Group of more than 20 galaxies, but Hubble’s vision takes us far beyond our celestial neighborhood. Galaxies are the visible foundation of the universe; each one a collection of stars, planets, gas, dust, and dark matter held together by gravity.

There are an estimated 100 billion galaxies in all of the observable universe. [1] . On the order of 100,000 galaxies make up the Local Supercluster, and about 51 galaxies are in the Local Group (see list of nearest galaxies for a complete list).

2025年4月4日 · A galaxy is any of the systems of stars and interstellar matter that make up the universe. Many such assemblages are so enormous that they contain hundreds of billions of stars. Galaxies usually exist in clusters, some of which measure hundreds of …

2021年1月12日 · Our universe includes a variety of astonishing and sometimes bizarre objects. Massive black holes so powerful, they swallow nearby objects. Galaxies that merge into giant swirls. Enormous stars that eventually explode and become supernovas. Neutron stars — objects so dense, one tablespoon of their material would weigh about 1 billion tons on ...

2023年9月14日 · NASA’s James Webb Space Telescope has peered into the chaos of the Cartwheel Galaxy, revealing new details about star formation... This landscape of “mountains” and “valleys” speckled with glittering stars is actually the edge of a …