Galaxies - NASA Science
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.
What Is a Galaxy? | NASA Space Place – NASA Science for Kids
2024年12月5日 · We live on a planet called Earth that is part of our solar system. But where is our solar system? It’s a small part of the Milky Way Galaxy. A galaxy is a huge collection of gas, dust, and billions of stars and their solar systems. A galaxy is held together by gravity. Our galaxy, the Milky Way, also has a supermassive black hole in the middle.
Solar System, Galaxy, Universe: What’s the Difference? - Science@NASA
2017年6月1日 · Galaxies come in many sizes. The Milky Way is big, but some galaxies, like our Andromeda Galaxy neighbor, are much larger. The universe is all of the galaxies – billions of them! NASA’s telescopes allow us to study galaxies beyond our own in exquisite detail, and to explore the most distant reaches of the observable universe.
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.
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.
Galaxy | Definition, Formation, Types, Properties, & Facts | Britannica
2024年12月21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. Virtually all galaxies appear to have been formed soon after the universe began, and they pervade all space that is viewable by modern telescopes.
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...
Stars and Galaxies | NASA Jet Propulsion Laboratory (JPL)
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 Earth.
Galaxies are cosmic islands of stars, planets, nebulas, gas, dust, and dark matter that are separated from one another in space but collectively help to tell the story of the universe. With the Hubble Space Telescope, we have begun to understand galaxies as …
Galaxies, stars and planets | OpenLearn - Open University
2012年9月8日 · This free course, Galaxies, stars and planets, is a general introduction, including scale of the universe from the very large to the very small; orbits and gravity; the Solar System; the Sun and other stars; galaxies and the composition of astronomical objects.
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