Photos of the Day

  On some nights it rains meteors. Peaking two nights ago, asteroid dust streaked through the dark skies of Earth, showering down during the annual Geminids meteor shower. Astrophotographer Juan Carlos Casado captured the space weather event, as pictured above, in a series of exposures spanning about 2.3 hours using a wide angle lens. The snowcapped Teide volcano of the Canary Islands of Spain towers in the foreground, while the picturesque constellation of Orion highlights the background. The star appearing just near the top of the volcano is Rigel. Although the asteroid dust particles are traveling parallel to each other, the resulting meteor streaks appear to radiate from a single point on the sky, in this case in the constellation of Gemini, off the top of the image. Like train tracks appearing to converge in the distance, the meteor radiant effect is due to perspective. The astrophotographer has estimated that there are about 50 Geminids visible in the above composite image -- how many do you see?

The Moon is especially lovely when it's low on the horizon and the terrestrial foreground adds a touch of depth to the scene. Here the full harvest Moon is seen setting over Calabasas Peak in the Santa Monica Mountains during morning twilight on September 19, 2013. Besides its beauty, there are four interesting aspects of the low Moon. Its orange color is due to absorption and scattering of light by the atmosphere and airborne aerosol particles. Much of the shorter wavelength blue and green light is removed from the Moon’s image, leaving red and orange to reach the observer’s eye.