Earth’s Overpowering Shadow
Cuts off moon’s light source
The waxing moon is the main attraction this week, beginning Thursday amid the stars of Taurus. Not 10 degrees from the moon’s outer edge shine the sisters of the Pleiades cluster, while beneath the moon shines the bull’s red eye, Aldebaran.
Friday, the gibbous moon and the red planet Mars spend the evening less than five degrees apart. Saturday, too, the moon remains just 10 degrees east of Mars.
Sunday the moon is in Gemini, roughly five degrees below golden Pollux and less than 10 degrees from blueish Castor. With the beginning of the new week, the moon passes through Cancer and on to Leo. Come Tuesday, the moon is little more than 10 degrees to the west of Regulus, the heart of Leo the lion, with golden Saturn another five degrees farther.
Wednesday’s full moon rises as the sun sets at 5:50, and now Regulus is two degrees away and Saturn five. At 8:53, the moon’s eastern edge, that closest to Saturn, begins to change color and hue as it slips behind Earth’s outer, penumbral, shadow.
Over the next 90 minutes, the whole of the moon falls into penumbra shadow, while the eastern edge grows darker and darker as it moves into Earth’s inner, umbral, shadow. At 10:01, the moon falls into total eclipse, reemerging at 10:51. Now the process reverses, and the moon brightens from east to west. By a little past midnight, it is again its normal self.
Even during the near-hour-long period of totality, however, the moon never truly disappears from sight. Instead, it takes on a deep, dark glow. What little light we see is first reflected and refracted off earth, then off the moon’s face before finally reaching our eyes.
Illustration: © Copyright 1925 M.C. Escher/Cordon Art-Baarn-Holland; Graphics: © Copyright 2007 Pacific Publishers. Reprinted by permission from the Tidelog graphic almanac. Bound copies of the annual Tidelog for Chesapeake Bay are $14.95 ppd. from Pacific Publishers, Box 480, Bolinas, CA 94924. Phone 415-868-2909. Weather affects tides. This information is believed to be reliable but no guarantee of accuracy is made by Bay Weekly or Pacific Publishers. The actual layout of Tidelog differs from that used in Bay Weekly. Tidelog graphics are repositioned to reflect Bay Weekly’s distribution cycle.Tides are based on National Oceanic and Atmospheric Administration and are positioned to coincide with high and low tides of Tidelog.