In Australia's Northern Territory, termites build mounds that are tall, thin, and aligned like compass needles. How and why the insects do this is not entirely clear. One entomologist offers some theories.For more global science stories, visit: http://www.world-science.org/NOVA is produced by WGBH in Boston. National corporate funding for NOVA is provided by The Boeing Company. Major funding for NOVA is provided by David H. Koch, the Corporation for Public Broadcasting, and PBS viewers.