What is defined as a system of stars, gas, and dust held together by gravity?

The term that describes a system of stars, gas, and dust held together by gravity is indeed a galaxy. Galaxies are enormous structures that can contain billions of stars, along with various amounts of interstellar gas and dust, all bound together by gravitational forces. They can vary significantly in size, shape, and composition, and each galaxy can host different types of celestial phenomena, including star formation, supernovae, and black holes.

Understanding galaxies is central to astrophysics and cosmology, as they are fundamental building blocks of the universe. There are different types of galaxies, such as spiral, elliptical, and irregular, each with unique characteristics, yet all share the common feature of being gravitationally bound systems.

In contrast, a constellation refers to a grouping of stars that appears as a distinct pattern in the night sky, often representing mythological figures or animals, rather than a physical collection of stars. The solar system specifically refers to the Sun and all celestial bodies that are bound to it by gravity, including planets, moons, asteroids, and comets, rather than an expansive collection of stars. A nebula is a cloud of gas and dust in space, often serving as a nursery for new stars, but it does not encompass the broader