This giant map of invisible dark matter recorded in four directions by the Canada-France-Hawaii Telescope during each season of the year was released on Jan. 9, 2012. The color inset shows the previous largest COSMOS dark matter map and the size of the full moon (as it would appear to the telescope) to scale. [CREDIT: Van Waerbeke, Heymans, and CFHTLens collaboration.]
Dark matter clusters and filaments constitute 98% of the matter in the universe. Mapping is possible through gravitational lensing effect, i.e., light paths from distant objects bent by gravitational pulls of the dark matter before reaching Earth.
A movie by the same name can be seen here.