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.

3 天之前 · Galaxies differ from one another in shape, with variations resulting from the way in which the systems were formed and subsequently evolved. Galaxies are extremely varied not only in structure but also in the amount of activity observed.

2024年10月22日 · Scientists sometimes categorize galaxies based on their shapes and physical features. Other classifications organize galaxies by the activity in their central regions – powered by a supersized black hole – and the angle at which we view them.

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...

2025年1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.

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.

There are probably more than 170 billion galaxies in the observable universe. Astronomers sort galaxies into three main types by their shapes: spirals, ellipticals, and irregulars, and further divide them into subtypes based on their particular characteristics. Find out more about one of the galaxies by selecting it below.

2024年7月27日 · Galaxies are the visible foundation of the universe; each one a collection of stars, planets, gas, dust, and dark matter held together by gravity. Hubble’s observations give us insight into how galaxies form, grow, and evolve through time. Credit: NASA's Goddard Space Flight Center; Lead Producer: Miranda Chabot; Lead Writer: Andrea Gianopoulos.

2019年1月4日 · Galaxies are composed of stars, dust and dark matter, all held together by gravity. Astronomers aren't certain exactly how galaxies formed. After the Big Bang, space …

2025年3月23日 · Galaxies are the building blocks of our universe. Their distribution isn’t random, as one might suppose. Instead, galaxies reside along unimaginably long filaments across the universe, forming...