A stellar nursery looks like the outline of a butterfly in this infrared image from Spitzer Space Telescope. The nursery, known as W40, contains hundreds of newborn stars. The heaviest of them are more than 10 times as massive as the Sun. Such stars are extremely hot, so they produce huge amounts of radiation and strong 'winds' of charged particles. The wind and radiation blow gas and dust away from the young stars, forming the butterfly's wings. The radiation causes gas in the nebula to glow, lighting up the wings. W40 is about 1,400 light-years from Earth. [NASA/JPL]