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Nature 401, 27-28 (2 September 1999) | doi:10.1038/43336

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Dark matter: Lumpy haloes spin faster

James Binney

More than 90% of the mass of the Universe is thought to be made up of dark matter. The density of this mysterious matter has been most precisely measured in the outer reaches of disk-shaped spiral galaxies, where very little light is emitted by stars.