Galaxy | Definition, Formation, Types, Properties, & Facts | Britannica
2025年1月11日 · galaxy, 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 - NASA Science
2024年10月22日 · Our home galaxy is called the Milky Way. It’s a spiral galaxy with a disk of stars spanning more than 100,000 light-years. Earth is located along one of the galaxy’s spiral arms, about halfway from the center. Our solar system takes about 240 million years to …
What’s a galaxy? All you need to know - EarthSky
2024年5月21日 · A galaxy is a vast island of gas, dust and stars in an ocean of space. Typically, galaxies are millions of light-years apart. Galaxies are the building blocks of our universe.
Galaxies—facts and information - National Geographic
2019年4月17日 · 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...
Galaxy Formation and Evolution - Center for Astrophysics
Galaxies are home to most of the stars in the universe, and they form the beads of the cosmic jewelry that defines structure on the largest scales. But galaxies haven’t always been around, and they have changed over the universe’s 13.8 billion-year history.
How Galaxies Work | HowStuffWorks
2023年11月8日 · A galaxy is a large system of stars, gas (mostly hydrogen), dust and dark matter that orbits a common center and is bound together by gravity — you can think of them as "island universes." There are many types of galaxies spanning all sorts of shapes and sizes.
Galaxies - HubbleSite
2024年10月28日 · Galaxies are vast cosmic islands of stars, gas, dust, and dark matter held together by gravity. Hubble’s keen eye has revealed intricate details of the shapes, structures, and histories of galaxies — whether alone, as part of small groups, or within immense clusters.
What is a galaxy? - Live Science
2021年8月25日 · 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...
Galaxies Over Time - NASA Science
2023年9月28日 · In our own local neighborhood of space, the Andromeda galaxy is headed toward the Milky Way for a possible future collision – many billions of years from now! Scientists today know that galaxies existed about one billion years after the Big Bang.
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 stars, whilst the biggest known galaxies can contain up to a hundred trillion stars.
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