To hunt for the "ninjas" of the cosmos -- dim objects that lurk in the vast dark spaces between planets and stars -- scientists are building the most sensitive set of wide-angle infrared eyes to date, a space telescope called the Wide-field Infrared Survey Explorer (WISE). WISE will scan the entire sky at infrared wavelengths, creating the most comprehensive catalog yet of dark and dim objects in the cosmos: vast dust clouds, brown dwarf stars, asteroids -- even large, nearby asteroids that might pose a threat to Earth.