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.
Nuclear materials get used in many forms of nuclear medicine -- everything from PET scans to chemotherapy uses them. Learn how nuclear medicine works.
First there was Volvo. Then came IKEA. Well get ready for the next major Swedish export: snus, a smokeless tobacco product, similar to dip or chew.