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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.
- List of galaxies
There are about 51 galaxies in the Local Group (see list of...
- List of galaxies
There are about 51 galaxies in the Local Group (see list of nearest galaxies for a complete list), on the order of 100,000 in the Local Supercluster, and an estimated 100 billion in all of the observable universe. [1] The discovery of the nature of galaxies as distinct from other nebulae (interstellar clouds) was made in the 1920s.
As of April 2022, the list included a total of 451 proper names of stars. [1] Of the roughly 10,000 stars visible to the naked eye, only a few hundred have been given proper names in the history of astronomy. [a] Traditional astronomy tends to group stars into constellations or asterisms and give proper names to those, not to individual stars.
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.
"The space distribution of stars and the chemical elements in the Milky Way Galaxy are discussed along with the large-scale structure and stellar content of galaxies, the solar motion, the stellar residual-velocity distribution, and the rotation of galaxies."
Stars are giant balls of hot gas – mostly hydrogen, with some helium and small amounts of other elements. Every star has its own life cycle, ranging from a few million to trillions of years, and its properties change as it ages. Stars form in large clouds of gas and dust called molecular clouds.
3 dni temu · 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.
