What is the term for the non-luminous matter believed to make up most of the universe's mass?

What is the term for the non-luminous matter believed to make up most of the universe's mass?

• A. Dark Matter
• B. Dark Energy
• C. Ordinary Matter
• D. Antimatter

Answer: (A)

Dark matter is the non-luminous material that has mass and produces gravity, yet does not emit, absorb, or reflect light. We detect its presence because galaxies rotate faster than they should if only visible matter were present, galaxy clusters hold together with more mass than we can see, and patterns in the cosmic microwave background and gravitational lensing require extra unseen mass. This is why we call it dark—its light is invisible, not because it isn’t there. It differs from ordinary matter, which you can see as stars and gas, and from antimatter, which would annihilate when it meets regular matter. Dark energy is a separate, pervasive influence driving the universe’s accelerated expansion, not the mass that clumps in galaxies.

Dark matter is the non-luminous material that has mass and produces gravity, yet does not emit, absorb, or reflect light. We detect its presence because galaxies rotate faster than they should if only visible matter were present, galaxy clusters hold together with more mass than we can see, and patterns in the cosmic microwave background and gravitational lensing require extra unseen mass. This is why we call it dark—its light is invisible, not because it isn’t there. It differs from ordinary matter, which you can see as stars and gas, and from antimatter, which would annihilate when it meets regular matter. Dark energy is a separate, pervasive influence driving the universe’s accelerated expansion, not the mass that clumps in galaxies.