- 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 the Milky Way galaxy that contains the Solar System
- Galaxy | Definition, Formation, Types, Properties, Facts | Britannica
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 millions of light-years across
- galaxy（英文单词）_百度百科
作为天文学术语，指由恒星、气体等构成的天体系统，如银河系（the Galaxy）和仙女座星系，并衍生出“星系团”“螺旋星系”等分类概念。
- Galaxies - NASA Science
Galaxy Basics 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
- Galaxies—facts and information | National Geographic
In our own galaxy, the Milky Way, the sun is just one of about 100 to 400 billion stars that spin around Sagittarius A*, a supermassive black hole that contains as much mass as four million suns
- Painting Galaxy Clusters by Numbers (and Physics) - NASA
Galaxy clusters are the most massive objects in the universe held together by gravity, containing up to several thousand individual galaxies and huge reservoirs of superheated, X-ray-emitting gas
- Galaxy - Elliptical, Spiral, Irregular | Britannica
In Hubble’s scheme, which is based on the optical appearance of galaxy images on photographic plates, galaxies are divided into three general classes: ellipticals, spirals, and irregulars
- Galaxy Types - NASA Science
They emit light across the electromagnetic spectrum, produce powerful particle jets, and can radiate thousands of times the energy emitted by a galaxy like the Milky Way
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