Interactive video lesson plan for: Dark Matter Matters

Nigel Goes to Space

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What is “Dark Matter” and how do we know it exists if we can’t see it?

Astronomers now know that most of the universe is invisible. As well as the stars, planets, galaxies, gas and dust, that we can see, there’s a lot of stuff we can’t see. There’s five times as much dark matter as there is ordinary matter.

Dark matter has not been detected directly, making it one of the greatest mysteries in modern astrophysics. Its hypothetical existence is inferred from gravitational effects on visible matter and gravitational lensing of background radiation, and was originally hypothesized to account for discrepancies between calculations of the mass of galaxies, clusters of galaxies and the entire universe made through dynamical and general relativistic means, and calculations based on the mass of the visible "luminous" matter these objects contain. The most widely accepted explanation for these phenomena is that dark matter exists and that it is probably composed of weakly interacting massive particles (WIMPs) that interact only through gravity and the weak force.

Nigel is an internationally acclaimed science populariser and author, specialising in astronomy and space.

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