Dark Matter

Astronomers have developed a new map of the universe showing normal matter in red, dark matter in blue, and stars and galaxies in gray. They used a technique called gravitational lensing to detect the dark matter because its only interaction with other matter occurs via gravity. They have found that dark matter is distributed as a loose network of filaments, which collapse due to gravitational interactions, into clusters that form a scaffold for the formation of stars and what not. Pretty cool.

Nature; 1/18/2007, Vol. 445 Issue 7125, p286-290, 5p