Astronomy Picture of the Day . ... Portuguese navigator Ferdinand Magellan and his crew had plenty of time to study the southern sky during the first circumnavigation of planet Earth. ... Cassiopeia A Light Echoes in Infrared . ... 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. ...