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.

May 2, 2025 · 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.

May 9, 2025 · Very generally speaking, galaxies are tens of thousands to hundreds of thousands of light-years across and have millions to several trillions of stars. Our Milky Way, for example, is about...

Apr 15, 2021 · Separated by millions of light-years of essentially nothing, galaxies are incredibly isolated, each one an island. Astronomers have identified three kinds of galaxies: spirals, …

1 day ago · Alongside a recent study published in Astronomy and Astrophysics, these images provide new insights into how the first galaxies formed over 13 billion years ago.

In this chapter, we start our exploration of the vast realm of galaxies. Like tourists from a small town making their first visit to the great cities of the world, we will be awed by the beauty and variety of the galaxies.

Galaxies are immense systems of stars, gas, and dark matter bound together by gravity. They vary in shape – spirals, ellipticals, and irregular formations. Governed by gravity, galaxies cluster in the cosmic tapestry, and the Milky Way is just one of billions in the universe.

Learn about galaxies near and far, from the earliest to form in the distant universe to stunning spirals in our neighborhood.

Galaxies are vast cosmic islands of stars, gas, dust, and dark matter held together by gravity. NASA’s space telescopes have revealed intricate details of the shapes, structures, and histories of galaxies — whether alone, as part of small groups, or within immense clusters.

Named galaxies This is a list of galaxies that are well known by something other than an entry in a catalog or list, or a set of coordinates, or a systematic designation.