Astronomy Picture of the Day . ... Cassiopeia A Light Echoes in Infrared . ... Two images of the nearby supernova remnant taken a year apart in infrared light appear to show outward motions at tremendous speeds. ... In continuing efforts to answer this question, astronomers have now discovered an Earth-like planet orbiting a distant normal star. ... No sudden, sharp boundary marks the passage of day into night in this gorgeous view of ocean and clouds over our fair planet Earth. ... Galaxies in View . ...