Astronomy Picture of the Day

Explanation: What's happening behind that island? Things both expected and unexpected. Expected, perhaps, the pictured rays of light -- called crepuscular rays -- originate from the Sun. Unexpected, though, the Sun was being partially eclipsed by the Moon at the time -- late last month. Expected, perhaps, the Sun's rays are quite bright as they shine through gaps in below-horizon clouds. Unexpected, though, the crepuscular rays are quite red, likely the result an abundance of aerosols in Earth's atmosphere scattering away much of the blue light. Expected, with hope, a memorable scene featuring both the Moon and the Sun, superposed. Unfortunately, from this location -- in Uruguay looking toward Argentina -- clouds obscured the eclipse -- which wasn't completely unexpected. However, after packing up to go home, the beauty of bright red crepuscular rays emerged -- quite unexpectedly. Oh -- and that island on the horizon -- it's really two islands.