The Mystery of Dark Matter in the Universe

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When astronomers look at the cosmos, they see galaxies rotating, stars forming, and cosmic structures spanning billions of light-years. Yet, the visible matter—the stars, planets, and gas clouds—accounts for only a small fraction of what is actually out there. Most of the universe appears to be made of an invisible substance known as dark matter.

Dark matter neither emits nor absorbs light, making it impossible to detect directly with telescopes. Scientists infer its existence from its gravitational effects. For example, galaxies spin so quickly that, without dark matter, they should fly apart. The fact that they remain intact suggests an unseen mass is holding them together.