Which term describes a large-scale structure in the universe that is composed of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity?

Which term describes a large-scale structure in the universe that is composed of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity?

• A. Galaxy
• B. Lunar
• C. Gravitational forces
• D. Nebula

Answer: (A)

Think of galaxies as massive, gravity-bound islands in the cosmos. They contain billions of stars and the remnants left by dead stars, plus vast amounts of interstellar gas and dust, all held together by the gravity of dark matter that forms an invisible halo around the system. This combination—visible matter plus dark matter bound by gravity—defines a galaxy, making it the best description of the term in question. A nebula, by contrast, is just a cloud of gas and dust, often a birthplace for stars, not a bound system that includes stellar remnants and a dark matter halo. The Moon (lunar) is a celestial body related to Earth, not a galaxy, and gravitational forces describe the interaction that binds structures together rather than naming the structure itself.

Think of galaxies as massive, gravity-bound islands in the cosmos. They contain billions of stars and the remnants left by dead stars, plus vast amounts of interstellar gas and dust, all held together by the gravity of dark matter that forms an invisible halo around the system. This combination—visible matter plus dark matter bound by gravity—defines a galaxy, making it the best description of the term in question. A nebula, by contrast, is just a cloud of gas and dust, often a birthplace for stars, not a bound system that includes stellar remnants and a dark matter halo. The Moon (lunar) is a celestial body related to Earth, not a galaxy, and gravitational forces describe the interaction that binds structures together rather than naming the structure itself.