Compass, in navigation, an instrument used to indicate directions. It ranks as one of the most important inventions ever made. The usual compass shows the cardinal points—north, east, south, and west—and a number of intermediate points. Most compasses are also graduated in the degrees of a circle, north being 0°; east, 90°; south, 180°; and west, 270°. Surveyors, however, reverse this arrangement and measure clockwise from the south, so that a bearing of 90° in a survey is west.
We first reported on the possibility of an invisibility cloak last year. Now a different invisibility cloak is making the news -- one that uses metamaterials to redirect light away from the wearer.
Uranium -- the stuff of futuristic energy and atomic weapons. Mining for this valuable element is anything but dull. Think you know how uranium mining works? Take this quiz to find out.