What is a cloud of interstellar gas and dust known as?

A cloud of interstellar gas and dust is known as a nebula. Nebulae play a crucial role in the lifecycle of stars and galaxies. They are often the regions where new stars are formed, as the gas and dust can collapse under gravity to create dense areas that ignite nuclear fusion. Nebulae can vary in type, including emission nebulae, which are glowing due to the ionization of gas, and dark nebulae, which are dense clouds that obscure light from objects behind them.

In contrast, a galaxy is a much larger system that contains many stars, star clusters, and nebulae, among other cosmic matter. An asteroid is a small rocky object that orbits the sun, primarily found in the asteroid belt between Mars and Jupiter, while a comet is a celestial object made of ice and dust that, when close to the sun, displays a characteristic glowing coma and tail. Each of these terms refers to distinct astronomical structures or phenomena, emphasizing the unique nature of a nebula in the cosmos.