You've heard of radioactivity. Uranium decay is another way of referring to radioactivity. Uranium decay is important for many reasons, including its use as a tool to measure large spans of geologic time. In addition, radon, a dangerous gas that can accumulate in confined areas in buildings, is one of the products of uranium decay.

Learn more about uranium decay at one of our newest FAQs!

http://www.usgs.gov/faq/index.php?action=artikel&cat=104&id=1189&artlang=en&highlight=uranium+decay&search=true

The mission of the Geomagnetism Program is to monitor the Earth’s magnetic field. Using ground-based observatories, the Program provides continuous records of magnetic field variations covering long timescales; disseminates magnetic data to various governmental, academic, and private institutions; and conducts research into the nature of geomagnetic variations for purposes of scientific understanding and hazard mitigation.

See Fact Sheet 2007-3092 for more information on "Monitoring the Earth's Dynamic Magnetic Field".