Current Solar X-rays: Current Geomagnetic Field: |
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The moon's southern limb will miss occulting Mars by about 40 seconds of arc in the Lehigh Valley. To give an idea of how close that is, there are 1,296,000 seconds of arc in a circle. Drawing by Gary A. Becker using Stellarium... |
Map by Gary A. Becker using Software Bisques's The Sky... |
Map designed by Gary A. Becker using Software Bisque's The Sky... |
Conditions had been dreary, damp, and rainy for days, and the National Weather Service showed the entire East Coast socked in with clouds and drizzle along the path of a spectacular grazing occultation of the moon and Mars. My friend Pete and I gave up our plans to drive to a nearby location in Pennsylvania or New York where the northern hemisphere of Mars with its white polar cap could be seen partially disappearing behind the southern limb of the moon. I also cancelled the event for about a half dozen of my students who were interested in viewing the near occultation from the Sky Deck atop the Collier Hall of Science at Moravian University. That is how dire conditions looked. Cloud cover was predicted by the NWS to be 95 percent at the time of the graze with areas of dense fog developing later that evening. * To my complete surprise, the infrared radar showed that cloudiness at 8 p.m. on December 7 was minimal with high, thin clouds present over most of the state. Denser, overcast conditions were still prevalent across the Mason-Dixon line and southeastern PA, where the boundary of a cold front was slowly making its way southward. * Since I had no way of accurately polar aligning an equatorial mount, I decided to keep it simple with my DSLR camera and a telephoto lens mounted to a tripod in anticipation of any clear spots that might develop. Pete also stood by his 11-inch Schmidt-Cassegrain ready to image some 30 miles to my south. Gradually, the sky began to cooperate, becoming mackerel in texture with high altocumulus clouds that allowed quick glimpses of the veiled moon and a reddened Mars surrounded by a colorful lunar corona. * I must have taken a hundred images with only a handful that I saved because of the difficulty in anticipating a proper exposure due to the scudding clouds. It became more overcast again with two thin levels moving at almost right angles to each other, one set from the east and the other from the north. I didn't realize it until later, but the southbound clouds were revealing the drier air from the cold front beginning to work its way into the area.
That's when the diamond in the rough vividly appeared next to the encroaching moon.
The ground temperature remained balmy in the 50's, but the sky went through a rapid cleansing and within 15 minutes, thinning puffs of rushing altocumulus were playing hide and seek with the moon, acting as a distinct boundary between clear and mostly cloudy conditions. By the time of closest approach at 10:52 p.m., the clouds had retreated southbound for both Pete and me, and through binoculars, a reddish diamond was nearly in contact with the full moon. * What a glorious sight and a wonderful Christmas gift, I thought. Both Pete and I were able to capture the event in different formats when the moon and Mars were at their closest, less than 40 seconds of arc in angular distance. By midnight, Mars could be discerned visually by placing a finger over the full moon, but that was not the case during the time when the Red Planet was closest to the moon. Binoculars, at a minimum, were necessary. Two hours later, as I finished writing my thoughts for this article, clouds had returned, and the moon and Mars were once again veiled. * For East Coast observers where clouds and precipitation prevent about half of anticipated astronomical events to be seen, this was a nice Christmas treat to an extremely rare astronomical event. Pictures are posted here. Happy Holidays. Ad Astra!
Map courtesy of the Royal Astronomical Society of Canada... |
During the majority of time leading up to the moon's closest separation from Mars, the sky was mostly cloudy. Gradually, the overcast became broken, and through one brief opening the moon and Mars were glimpsed along with a beautiful corona. Coronas are diffraction effects caused by minute water droplets or ice crystals bending the moonlight into a blue interior surrounded by a reddish exterior. Gary A. Becker image... |
This spectacular picture was recorded by Peter K. Detterline in Douglassville, PA. It shows a greatly magnified image of Mars when it was closest to the moon taken with an 11-inch, Schmidt-Cassegrain reflector. Peter took several thousand rapid fire images of the event at about 100 frames per second. A computer program then picked out the best 500 frames and these were stacked to lessen the atmospheric turbulence which is the biggest factor in reducing image detail. Great job, Pete. You should be teaching astrophotography at Moravian University. Peter K. Detterline image... |
This is a more tradition view of the event as seen through binoculars or a small telescope. All of my images were recorded with a tripoded Canon 80D, DSLR camera and a 70-200mm Canon telephoto lens coupled to a 2X extender for an effective focal length of 640mm (12.8 power). Images of Mars were shot at F/14, ASA 800 for 1/100th second. Images of the moon were taken at 1/800th second. The two images were then combined. Gary A. Becker photography... |
These six photos show the progression of the December 7 near graze of the moon and Mars. The closest angular distance of the moon to Mars occurred at 10:52 p.m. EST (far left bottom image). Gary A. Becker photography... |