The Waxing Crescent Moon returns to the evening sky Thursday, September 9, its fingernail-shaped thin crescent barely visible above the western horizon some ½ hour after sunset. On Friday and Saturday evenings, the fatter and brighter crescent moon lies close to the brilliant white planet Venus. By early next week, the thickened crescent moon will lie in a favorable southerly position for evening telescopic viewing. September evenings in San Diego are often a perfect time to turn a telescope on the moon and note its hundreds of visible craters. Calmer weather conditions this time of year tend to minimize atmospheric turbulence over San Diego's coastal and inland areas, and that contributes to crisper telescopic views.
The Zodiacal Light, which can appear as a diffuse, pillar-shaped glow in the eastern sky for up to an hour before dawn, will be quite conspicuous at dark locations this weekend. The subtle glow is caused by the sun's light reflecting off dust particles floating in space in the plane of our solar system. In the sky, this reflected light appears superimposed along the string of constellations we know as the zodiac, and especially those zodiacal constellations closest to the direction of the sun. An old name for this phenomenon is "false dawn" -- a good description of the effect under clear and very dark skies.
The Waxing Crescent Moon returns to the evening sky Thursday, September 9, its fingernail-shaped thin crescent barely visible above the western horizon some ½ hour after sunset. On Friday and Saturday evenings, the fatter and brighter crescent moon lies close to the brilliant white planet Venus. By early next week, the thickened crescent moon will lie in a favorable southerly position for evening telescopic viewing. September evenings in San Diego are often a perfect time to turn a telescope on the moon and note its hundreds of visible craters. Calmer weather conditions this time of year tend to minimize atmospheric turbulence over San Diego's coastal and inland areas, and that contributes to crisper telescopic views.
The Zodiacal Light, which can appear as a diffuse, pillar-shaped glow in the eastern sky for up to an hour before dawn, will be quite conspicuous at dark locations this weekend. The subtle glow is caused by the sun's light reflecting off dust particles floating in space in the plane of our solar system. In the sky, this reflected light appears superimposed along the string of constellations we know as the zodiac, and especially those zodiacal constellations closest to the direction of the sun. An old name for this phenomenon is "false dawn" -- a good description of the effect under clear and very dark skies.