StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

SEPTEMBER 2013

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

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889 SEPTEMBER 1, 2013: Blues over the Blue Moon: At the beginning of my astronomy course, I work with my students on a unit involving astronomical misconceptions. One perception covered is that of the blue moon; when two full moons occur within the time span of one month, the second full moon is termed the blue moon. So you can imagine my surprise when I saw a NASA release claiming that the August 20th full moon was a blue moon. “Impossible,” I thought! Full moons occur with a frequency of approximately 29.5 days, so a blue moon can only occur near the very end of a month if the first full moon happened near the very beginning. The evolution of the blue moon began with The Maine Farmers’ Almanac (1819-1968). Between 1932 and 1957 the Almanac maintained a seasonal scheme for determining when a blue moon occurred. Their blue moon formula followed the solstices and the equinoxes which occur around the 21st of March, June, September, and December. Moon names in the Almanac were synchronized to an ecclesiastical calendar which was mostly set to the yearly cycle of the sun. Simply said, a full moon with a particular name had to occur at the same time of the year. When there were four full moons in a season, an event that occurred about every 2.6 years, the calendrical sequence was thrown out of order. To correct for this and keep the moon names concurrent with the year, the third full moon of a four full moon cycle became known as the blue moon. Our modern definition of a blue moon, two full moons occurring within a calendar month, stems from the misunderstanding of The Maine Farmers’ Almanac’s rule which was first published in a 1946 article in Sky and Telescope magazine. The new two full moons in a month idea caught on and by the 1980s this definition rose to supremacy and was accepted by the astronomical community worldwide. Message to NASA... Stick to spaceflight.

890 SEPTEMBER 8, 2013: Moon and Venus Embrace: I got involved with astronomy through aesthetics, although at the time I had no idea what that meant. As a kid, the night sky was a very scary place, but the beauty and mystery of those stars flung against the heavenly vault compelled me to look up. On one blustery autumn evening, while walking to a cub pack meeting, I did just that and witnessed a bright meteor scorch the blackness. That meteor got me to reading, particularly our home encyclopedia, The Book of Knowledge, which provided me with answers; and here I am, some 55 years later still intrigued with the mystery and wonder of it all. I have always called astronomy, “the beautiful science,” and I invite you to partake in that beauty by viewing the heavens about 45 minutes after sundown on Sunday, September 8, when the second and third brightest sky objects, the moon and Venus, will be in close conjunction, under two degrees apart from each other. Check out the moon the day before, about 30 minutes after sundown. It will be very low in the WSW. Sweep the horizon with binoculars to enhance the contrast of the razor thin crescent moon against the bright sky background. Even if you don’t locate the moon, look for Venus above and to the moon’s left because that is where the moon will be located on Sunday. Venus will be found about one binocular field above the horizon, 45 minutes after sunset, and easily seen to the unaided eye. On Monday evening, Luna will be next to dazzling Venus. As dusk deepens, you’ll notice even the unlit portion of the moon glowing from the reflected light of a nearly full Earth as seen from the moon. That’s called earthshine, and it will appear spectacular through binoculars. You’ll also notice Saturn above and to the left of Venus. A thicker, brighter crescent moon will be situated about five degrees to Saturn’s right on Monday. Pictures are online at www.astronomy.org/.

891 SEPTEMBER 15, 2013: Harvest Moon: One of Many Names: The autumnal equinox, when the sun is crossing the celestial equator southward bound, and day and night stand equal around the world, occurs in just a week on September 22 at 4:44 p.m. EDT. Three days prior to the equinox on the 19th, the moon is full, and because this full moon is closest to the autumnal equinox, it is named the Harvest Moon. It is probably the most famous of the seasonal moon names and universally recognized from mid to northern latitude locales of North America and Europe. The Harvest Moon results from the shallow angle that the moon’s orbit makes to the horizon during the time of the autumnal equinox. On the night of full moon, Luna rises at or very near the time of sundown. For the next few days the moon’s orbital motion carries it about 13 degrees eastward each day, but that motion does not take it very far below the horizon, allowing the moon to rise at nearly the same time for a few days. This situation allowed farmers to continue harvesting their crops by the light of the rising moon as daylight faded, hence the name Harvest Moon. Moon names associated with the other months follow: January—Old Moon, Moon after Yule or Wolf Moon; February—Snow Moon or Hunger Moon; March—Worm Moon, Crust Moon, Sap Moon, Crow Moon, or Lenten Moon; April—Easter Moon, Paschal Moon, Pink Moon, Sprouting Grass Moon, Fish Moon, or Egg Moon; May—Corn Planting Moon, Flower Moon, or Milk Moon; June—Rose Moon or Strawberry Moon; July—Thunder Moon, Buck Moon, or Hay Moon; August—Sturgeon Moon, Red Moon, Green Corn Moon or Grain Moon; September—Harvest Moon, Corn Moon, or Fruit Moon; October—Hunter’s Moon, Blood Moon, or Sanguine Moon; November—Frosty Moon or Beaver Moon; and December—Cold Moon, Moon before Yule, or Long Night Moon.

892 SEPTEMBER 22, 2013: Danger, Will Robinson! Massive Comet Approaching!: If the first three words of this StarWatch missive make any sense, then you are either an aficionado of bad science fiction or are just plain getting old. I fit into the latter category. Lost in Space, a 1960s “futuristic” version of Swiss Family Robinson and Robinson Crusoe, pitted the evil Dr. Smith against the well-intentioned Robinson family, lost while trying to reach Alpha Centauri, the closest star system to our sun. In the 83 episodes that aired, they never made it. Likewise is the space saga of ISON, potentially one of the great comets of the last 50 years, and now headed sunward for a close encounter with Sol on Thanksgiving Day. The big question is, “Will Comet ISON make it past the sun or will Sol simply cause it to go PUFF? Comets are loose aggregates of mainly ice (water) and dust and look similar to a dingy snow pile on a mall parking lot that’s been exposed to traffic for several weeks. Jab it with a snow shovel and it seems impenetrable; but pit it against the blistering heat and gravity of the sun and the comet’s rigidity becomes more like cotton candy. Currently, Comet ISON is a Southern Hemispheric object with a tail of about two degrees and still only visible through larger telescopes. Astronomers predict that ISON will peak at about the brightness of Venus on Thanksgiving as it passes within 700,000 miles of the sun’s photosphere (visible edge) and gets cooked to temperatures of nearly 5000 degrees F. If the comet survives its solar passage on November 28, ISON will rapidly move northward by the first week in December as an easily seen morning object with an impressive tail. By December’s third week, ISON will become visible in the evening as well as the morning sky; and finally after Christmas, it will be seen all night long, that is unless Comet ISON becomes “lost in space” by the sun’s powerful forces. Optimistically, this year will end with a beautiful comet gracing our Yule sky.

893 SEPTEMBER 29, 2013: Opa: I’ve often wondered what spurred me as a kid to look at the sky. Perhaps it was the bright meteor that I saw on my way to a cub pack meeting or a teacher asking me if the cosmic information that she was conveying to her class was accurate. Then there was my poor father who I bombarded with a gazillion questions until one day he sighed and said, “Son, I just don’t know.” My response was, “Well, dad, give it your best shot.” And on it went… My grandfather, Ewald Marcus (1893-1988), must have also played a role when he regaled me with vivid stories of his life, often using English and German words, interspersed within the same sentences as he spoke. As a student in the gymnasium, he was switched by his teacher when he conjectured about life on distant worlds in our galaxy. When he was 16 in 1910, he and a friend attended a May carnival in his hometown of Solingen-Wald. As the light from late afternoon waned into twilight, and then to darkness, there low in the sky was the bright gossamer tail of Halley’s Comet, stretching, as he put it, “from horizon to horizon.” The sheer surprise of its appearance always brought awe and wonder to his voice whenever he told me the story. As a German infantry soldier fighting on the Russian Front during WWI, my grandfather volunteered to take over culinary responsibilities when the cook in his regiment was killed. Ewald was an excellent, self-taught chef, and according to him, making a good meal was mostly a function of multiplying the correct ingredients by the number of hungry men who were to be served. My grandfather never received a complaint. At night when his chores were completed, he would often go outside and sit on a chair in the snowpack, reading the German newspaper by just the light of the moon. In the distance, hungry wolves howled at the stars, his “hooowing” sounds sending tingles up my spine. Opa died when I was 38, on my favorite day of the year, the summer solstice.

[September Star Map]

[September Moon Phase Calendar]