Since their discovery 120 years ago, strangely luminescent clouds called noctilucent clouds have been creeping slowly toward the equator. Once confined to Earth's poles, the bizarre clouds have now been spotted above central Colorado, and they appear to be getting brighter and more numerous, too, said David Rusch, a University of Colorado atmospheric scientist. This month, NASA plans to launch the $110 million AIM (Aeronomy of Ice in the Mesosphere) mission to measure noctilucent clouds and the circumstances in which they form - which may be linked to climate change. The satellite will measure air temperature and pressure, moisture content...