StarWatch for the greater Lehigh Valley
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DECEMBER  2020

DECEMBER STAR MAP | MOON PHASE CALENDAR | STARWATCH INDEX | NIGHT SKY NOTEBOOK

Print Large Sky Charts For 9 p.m. EST:   NORTH | EAST | SOUTH | WEST | ZENITH

[Moon Phases]

CURRENT MOON PHASES

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CURRENT MOON

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1268    DECEMBER 6, 2020:   Good Geminid Hunting
You will not need bullets or arrows to bag a Geminid, only clear skies to make them visible, abundant clothing to ward off the cold, and a shot of insomnia to keep you awake. From the morning of Sunday, December 13 into the morning of Monday, December 14, one of the great meteor showers of the year is at its best. Under perfect conditions, the Geminids can produce as many as 150 shooting stars per hour, but expect those rates to be more than halved under the suburban skies of the East Coast. Even if you are witnessing 30-50 meteors per hour, that still beats the best dark sky rates of virtually any annual shooting star event. Geminids enter Earth’s atmosphere at a medium pace, 22 miles per second (35 km/s), with some being exceedingly bright, but cloudy late fall weather, abundant moonlight, and wintery conditions have kept the Geminid meteor shower from becoming as popular as the August Perseids. You can scratch the moonlight for this year. The moon is new, but the cold and cloudiness are yet to be determined. Meteors from an organized shower diverge from a small area of the sky called the radiant. For the Geminids this position is located just a few degrees to the northwest (to the right and above) of the bright star Castor (see map here), the mortal twin of the Gemini brothers. Their origin stems from the debris discarded by the small asteroid, 3200 Phaethon, most likely a comet turned asteroid orbiting the sun. Currently, there are about a dozen annual meteor events associated with asteroids. Understanding that the meteor you have just witnessed is a Geminid is simple. Its path will be traceable back to the radiant position near the bright star Castor. To find the radiant, begin with Orion, the greatest hunter in mythology, at 10 p.m. in the ESE. Seven stars form his body, two for the shoulders, three for his narrow waist, and two luminaries for Orion’s knees or legs. They are all bluish in appearance except for orangey, “red” supergiant Betelgeuse, the shoulder star on the left side of the Hunter as we view him in the sky. Orion, in Robert Frost’s poem, The Star-Splitter, “…always comes up sideways, / throwing a leg up over our fence of mountains, / and rising on his hands, he looks in on me…” You’ll see him that way in the 8 p.m. to 11 p.m. time slot of early December. From Betelgeuse, move catty-corner to Rigel, a blue supergiant, and most of the time, the brightest star of the Hunter. Connecting Betelgeuse and Rigel, move left two of their lengths. You will land above two bright, closely spaced, white stars which are the heads of the Gemini Twins. The star closest to your extended line is Castor, the region from which Geminid meteors will be radiating. Meteors will be plentiful coming from this locale, particularly after midnight on the morning of December 13 through the morning of December 14. Wishing everyone good Geminid hunting!

[Geminid Radient]
"X" marks the radiant of the Geminid Meteors Shower which will have maximum counts on the morning of December 14. Gary A. Becker map using Software Bisques', The Sky...
 

1269    DECEMBER 13, 2020:   Faith in a Star
What star is this with beams so bright, / More lovely than the noonday light? / ‘Tis sent to announce a newborn king, / Glad tidings of our God to bring. The words of the French hymnist, Charles Coffin (1676-1749), encapsulates the joy and the mystery surrounding the Star of Bethlehem which graced the sky according to biblical accounts at the time of Christ’s birth. Astronomers have devised several storylines about the Star based upon biblical passages, historical information, and the backdrop of sky events. My favorite representation is a triple conjunction or coming together (three times) of the planets, Jupiter and Saturn, that began unfolding in the spring of 7 BC, and culminated in a loose grouping of Jupiter, Saturn, and Mars in February of 6 BC. If you’d like an in-depth look into the Star, I would suggest Courtney Roberts, The Star of the Magi, New Page Books, 2007. The celestial storyline that Roberts promotes fits well within the second of three taxation/census decrees which occurred during Augustus Caesar’s reign and the death of Herod the King as reported by the Roman/Jewish historian, Flavius Josephus. The astrological implications of Jupiter, Saturn, as well as the location of the triple conjunction in the constellation of Pisces the Fish, were key factors in motivating the Zoroastrian priests, the Magi, to make the journey (on horseback) from the east to Jerusalem to seek the discovery of the Christ Child. For the next two weeks, Christians and everyone else worldwide can experience a similar celestial sight that the Wise Men viewed when they saw the Star that changed the world over two millennia ago. Over the past summer and throughout the fall, Jupiter has been moving closer to Saturn. These were the two major players in the Star of Bethlehem saga. According to Zoroastrian prophecy/astrology, Saturn was considered to be the luminary most associated with the Hebrew people. Jupiter was the chief god. The Magi saw the triple conjunction in the House of the Hebrews, now Pisces the Fish. This time the conjunction is happening on the border of Capricorn and Sagittarius and Mars has no role. Despite the differences the excitement of witnessing a similar event during the Christmas Season should not be overlooked. During this week, Jupiter moves towards Saturn, rapidly closing the gap from just less than one degree on Sunday, December 13, to 0.2 degree, less than half the diameter of the moon by the following Saturday, December 19. Monday, December 21, the shortest day of the year, brings Saturn and Jupiter to their closest separation, 1/5 the diameter of the moon or 0.1 degree in the southwest about 30 minutes after sundown. For southeastern PA that is about 5:10 p.m. The question that some enthusiasts have been asking is whether the eye will be able to distinguish Jupiter from Saturn or will they appear as one object? I personally believe that under close scrutiny, they will be seen as separated. The last time that Jupiter and Saturn were closer and easily visible was on March 4, 1226 AD. Their separation was only 1/60th of a degree less than the conjunction on December 21. The two planets will not be closer again until 2080, March 15. Make sure you have a good southwestern horizon. Binoculars will enhance the view but are not necessary to enjoy this event. Finally, do not expect a …star with beams so bright, unless there is a Christmas miracle. The conjunction will be beautiful to behold, but not much brighter than Jupiter itself. Pictures are here. Have a blessed Holiday!

[Geminid Radient]
The developing Jupiter (brighter)-Saturn conjunction taken on December 8. Gary A. Becker image at an effective focal length of 56mm (1.1x)...

[Jupiter-Saturn Conjunction]
December 10, Gary A. Becker image at an effective focal length of 72mm (1.4X)...

[Altocumulus Clouds at Sundown]
Can you find the UFO in this picture. It looks like a cloud. Actually these are altocumulus clouds catching the last rays of sunlight on the evening of December 13. It was a nice ending to the day. Gary A. Becker image...
 

1270    DECEMBER 20, 2020:   Jupiter-Saturn Conjunction and Much More
This Monday finds Jupiter and Saturn at their closest, easily visible separation in nearly 800 years (1226 AD). Weather permitting, it will be a must-see event occurring low in the southwestern sky about 30 minutes after sundown, and it is a very nice representation of the Star of Bethlehem. I have been watching the two planets drawing closer to each other for months, and last Thursday, a day after the big snow, with the moon only 12 degrees to the east of the pair, I was able to observe and photograph that the angular separation between Jupiter and Saturn was less than the moon’s angular diameter which was just over one-half degree. Photos of the approach of the two planets can be found here and in the previous week’s StarWatch. There was a closer conjunction on July 16, 1623, but that occurred only 13 degrees from the sun in the evening sky and would have been difficult to observe; hence most astronomers use the 1226 event as the benchmark. Jupiter and Saturn will not be closer together until March 15, 2080. Do not despair if the 21st of December is cloudy. The next four days, right through Christmas, still brings Jupiter and Saturn closer together than the angular diameter of the moon. As the moon works its way eastward across the sky, December 23 sees Luna as a waxing gibbous, just under six degrees from Mars, and easy to spot in the south right after you have made your observation of Jupiter and Saturn in the southwest. Just look for the moon. By December 27 a fat waxing gibbous moon is in conjunction with the bright star Aldebaran in the V-shaped constellation of Taurus the Bull. Luna is full on the 29th. By New Year’s Eve the waning gibbous moon slides past the bright star Pollux in the constellation of Gemini the Twins. January 3 sees the moon near Regulus of Leo the Lion. Headed into the morning sky, a waning crescent moon passes Spica in Virgo the Virgin on January 6-7. As a finale to the present lunar cycle, a razor thin crescent approaches Venus low in the southeast in morning twilight on January 11. Luna is new on January 13. In addition to the super close conjunction taking place on the 21st, 5:01 a.m. on the same day marks the winter solstice, low sun and the shortest day of the year for the northern hemisphere. It also represents high sun and the longest day of the year for the southern hemisphere. For 40 degrees north, basically the latitude of Philadelphia, the sun rises farthest south from east and is only 26.5 degrees above the horizon at “high” noon. The sun sets the farthest to the south of west. Philly gets just over nine hours of sunlight during the course of a day, less farther north and more if you live farther south. That will expand to 12 hours by the vernal equinox, and 15 hours of sunlight by the summer solstice. Bring it on! I can’t wait!

[Jupiter-Saturn Conjunction]
The distance between Jupiter (brighter) and Saturn is less than one half degree. The proof lies with the moon which on December 17 was 31.5 minutes of arc in angular diameter. Jupiter was only 26.5 minutes of arc in parting from Saturn. The minimum departure on December 21 will be only 6 minutes of arc. There are 60 minutes in one degree. Gary A. Becker image at an effective focal length of 112mm (2.24X)

[Jupiter-Saturn Conjunction]
To show how close Jupiter and Saturn really are, the moon was added at the same magnification. It was in the sky at the same time that the photo of the conjunction was taken, but not in the same postion as indicated in the photo. The photo was taken on the evening of December 18. Gary A. Becker image at an effective focal length of 320mm (6.4X)...

[Jupiter-Saturn Conjunction]
FINNALY, a marginally usable night occurred on December 23 after four cloudy nights in a row. The separation of Jupiter from Saturn was 15 minutes 53 seconds or about half the angular diameter of the moon. Note that in the interim Jupiter passed Saturn and is now in the lead. Gary A. Becker image at an effective focal length of 320mm (6.4X)...
 

1271    DECEMBER 27, 2020:   2021: Solar System on Parade
Adios, 2020 and Hola, 2021. I am going to be highlighting some of the biggest close encounters involving the sun, moon, and planets during 2021. These will be mostly evening happenings because they fit better with our waking hours; however, the two biggest events of 2021, a solar and a lunar eclipse occur during the morning hours. Angular separations are given in degrees with the full moon’s diameter equal to one half degree. Jan. 10 finds a close association of Jupiter, Saturn, and Mercury very low (4 degrees) in the ESE about 30 minutes after sundown. You’ll need transparent skies and an impeccable SW horizon to pick out the grouping. Consider bringing along binoculars to make the view more enjoyable. Mercury continues to move away from the sun reaching its best position low in the WNW about 45 minutes after sundown on Jan. 24. Feb. 18 sees the moon slide under Mars (4 degrees separation), due south in the early evening sky. A better Moon-Mars conjunction occurs on Mar. 19 with the separation reduced to 2.75 degrees. In May brilliant Venus returns to the evening sky. Luna is next to Venus (1 degree) on May 12, Mercury on May 13 and above Mars on May 15, all 30 minutes after sundown in the WNW. The moon straddles a widening Jupiter and Saturn in the dawn skies of May 4, May 30, June 1, and June 28 (after midnight). Another very close conjunction of Mercury and Venus happens on May 28, low in the WNW, 30 minutes after sundown. The two interior (inferior) planets are separated by less than the moon’s width, another wonderful opportunity to spot two planets within the same field of view produced by a small telescope or spotting scope. At a minimum, binoculars will be needed to see Mercury because of its faintness. The moon stands by Venus after sundown on June 11, but probably June 10 is the most noteworthy day of the year for astronomy. Hey, it’s my birthday. What would you expect? With proper filtration, you will be able to witness about 75 percent of the rising sun eclipsed by the moon. The event will be best seen from Ontario, Canada as an annular or ringed eclipse. In the mid-Atlantic, the moon doesn’t leave the sun until about 6:30 a.m. when Sol will be a comfortable 9 degrees above the NNW horizon. Get your solar filters straight away. Another close encounter of two planets happens on July 12 after sundown when Mars and Venus will be separated by just over half a degree. Through binoculars you’ll be able to compare their closeness to the thin crescent moon just 6 degrees above the pair. Aug. 18 finds Mercury and Mars separated by less than 1/4th the diameter of the full moon, 30 minutes after sundown, a scant 2 degrees above the western horizon. A thin, waxing crescent moon hovers above Venus in the SW on Oct. 9. Their separation will be just over 2 degrees. A few days later on Oct. 14 the waxing gibbous moon finds itself between Jupiter and Saturn in the evening sky. This is repeated on Nov. 10 and Dec. 7 when Venus joins the loose association. Another must-see event transpires on the morning of Nov. 19, when Luna is hidden in Earth’s shadow. The lunar eclipse which favors North America and the Pacific starts at 2:19 a.m., EST. Greatest depth into the Earth’s shadow takes place at 4:05 a.m. when 97.5 percent of the moon will be darkened. Binoculars will enhance the colors which should be vivid. On New Year’s Eve morning, Luna hangs with Mars an hour before sunrise. Looking forward to a return to normalcy in 2021. Keep looking up, folks! Ad Astra!

[Lunar Halo]
FINNALY, a marginally usable night Gary A. Becker image...
 

[December Star Map]

[December Moon Phase Calendar]
 

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