StarWatch: Moravian University Astronomy

DECEMBER 2023

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1424 December 3, 2023: The Big One: Geminid Meteors: During the late evening of Wednesday, December 13, and the morning of Thursday, December 14, the most plentiful annual meteor shower of the year takes place. Under perfect conditions, the Geminid Meteor Shower can produce as many as 120 shooting stars per hour; however, those numbers are more than halved in the light-drenched suburban areas of the East Coast. * Geminids move relatively slowly, and some can be exceedingly bright. Still, cloudy weather and wintery temperatures have kept them from attaining the popularity of the August Perseids. * Meteors from an organized shower diverge from a small region of the sky called the radiant, which for the Geminids, is located just a few degrees to the northwest of the bright star Castor, the mortal twin of the Gemini brothers. * To find the radiant, begin with Orion, the greatest Hunter in mythology. Seven stars form his body: two for the shoulders, three stars for his narrow waist, and two luminaries for Orion's knees. 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. Cattycorner to Betelgeuse is Rigel, a blue supergiant and, most of the time, the brightest star of the Hunter. Connecting Betelgeuse and Rigel, and using the distance between these two luminaries as a yardstick, move left and up two of these lengths, and you will be above two bright, closely spaced, white stars, which are the heads of the Gemini Twins, Castor and Pollux. The bright star closest to your line of sight is Castor, the region from which Geminid meteors will fly. Go below for a map. * The meteoroids, the tiny specks of dislodged cometary dust that blaze into Earth's atmosphere, are moving parallel to each other in an analogous fashion to the sides of a road on a straight section of a highway. The thoroughfare diverges from a vanishing point in the distance called the radiant. * Geminid meteoroids originate from the debris discarded by a periodic comet-turned-asteroid, 3200 Phaethon, with a 1.4-year orbital period around the sun. Comets can suffer numerous fates, like being destroyed by plowing into or coming too close to the sun's radiant heat. The outer planets, but mainly Jupiter, can eject them from the solar system, or they can systematically reduce their elongated orbits until some lose their comet-like identities and become asteroid-behaving objects orbiting the sun. * Geminid meteors will be plentiful mainly after midnight on the morning of December 14, but for the moment, go outside and see if you can find the location of the radiant. That will prepare you for how you want to orient yourself on maximum night. Remember to check your inventory of heat-retaining clothing too! Overdress, since it will most likely be the cold that drives you indoors on Geminid maximum night. * Also, do not worry about the moon with this season's meteor shower because Luna is only hours past its new phase. Wishing everyone good Geminid hunting. Ad Astra!

1425

December 10, 2023: Showtime for the Geminids

As holiday lights continue to pop up across the Lehigh Valley, there is a celestial light show that is rapidly gaining strength. Geminid meteors are already flying this week, and their numbers will continue to climb throughout the evening hours and mornings of December 12/13 and 13/14, the predicted time for a broad maximum of activity. If this shower occurred during the summertime, undoubtedly the Geminids, rather than the August Perseids, would be the biggest shooting star event of the year, outpacing the Perseid activity by a margin of two to one. * Meteor showers arise from the debris comets release as they orbit the sun. When their dross crosses near enough to Earth’s orbital plane, these particles enter the atmosphere, producing the meteor phenomenon, cylinders of glowing (ionized) air as the rapidly moving dust grains are ablated (vaporized) from the friction with the air. * Until recently, the Geminids had no comet progenitor. Then in 1983, an Apollo class asteroid, a minor planet that has its closest distance from the sun within Earth’s orbit, was detected by British astronomers Simon F. Green and John K. Davies, and the Infrared Astronomical Satellite. Named 3200 Phaethon, it was discovered to have a similar orbital path to the Geminids and a period of only 524 days. Phaethon careens within 13 million miles of the sun at its closest approach, a near record for asteroids. At this distance, where temperatures are hot enough to melt lead, virtually all tail-forming volatiles have been vaporized (sublimated), leaving 3200 Phaethon similar to a large, low-density ball of dust. The discovery of Phaethon and its relationship to the Geminids gave credence to a proposed theory that some comets never die. They spend their retirement years as asteroids when their ices are gone and their orbits are perturbed into the asteroid belt by the giant planets, in this case, Jupiter. * Meteor observing was responsible for my getting interested in astronomy. Not having enough money to buy a telescope and not knowing what to purchase, it was just as easy to recline in a chaise lounge under the stars in the summer or nestle into a sleeping bag during the fall and late spring, to watch for shooting stars. * However, winter and the Geminids are a whole different story. The longest that I have survived watching for this December shower was just under four hours, and that was bundled up in several sleeping bags and numerous thermal clothing layers. The temperature was in the teens that evening. * Watching for meteors during the frosty weather months is not the same as skiing or snowboarding, where increased physical activity keeps you cozy despite the cold. You are lying motionless, and the damp chill of the night air seeps in rapidly. I suggest going outside for 30 minutes at a time, then getting comfortable again before returning into the cold. * Geminid meteors will be visible as soon as it gets dark. Still, optimal conditions occur after midnight when the radiant, near the bright star Castor in Gemini the Twins, gains some altitude and our region of the world plows into the swarm. For the East Coast, the shower is forecast to produce maximum activity during the early afternoon of December 13, so that rates should be high on the mornings of the 13th and on the 14th. Bundle up, look up, and enjoy the Geminids, the best of the best meteor shower of the year. Go above this article for a locator map. Ad Astra!

When this picture of the Big Dipper was taken back on October 12th from Hanksville, Utah, it was just beginning its upward climb around 1 a.m. Now, two months later the Dipper is engaged in this same maneuver around 9 p.m. By mid-February the Dipper will be in this position as soon as it gets dark, a sure indication that spring and warmer weather awaits. Image by Gary A. Becker...

1426 December 17, 2023: Sometimes I Just Want to Scream!: Every time I introduce the basic way that stars are classified, I can imagine the mental gymnastics that are occurring in my students' brains-OBAFGKM. Oh, Becker's Astronomy Field Guide Kills Me, a Penn State student once wrote as a mnemonic. I tell my learners he failed the class, but that's not true. He did pretty well, as I recall. "Why not ABCDEFG? To make things simpler," I retort. * In the beginning, before quantum mechanics (the physics of atoms), the key to a fundamental understanding of stars, astronomers analyzed the dark absorption lines of stellar spectra and categorized them in what they thought was a proper sequence. However, as we began to understand how atoms behaved, we realized that these spectra were created by the dance of an atom's outer electrons, absorbing discrete amounts of energy that formed the dark lines superimposed across the continuum (the rainbow of colors). This was the key to understanding the composition of the stars. Understanding the ratio of line intensities among the different elements was found to be a function of the temperature of the star, another great achievement. * Rather than keeping the sequence of lettering and aligning it with the new information, the old classification system was rearranged into a new, out-of-order, alphabetic, temperature sequence, which is understandable to astronomers, but challenging for students taking an introductory astronomy course. * Stellar temperatures can be hot enough to cause ionization. That is when an outer electron with a negative charge "flies the coup." What is left behind, now called an ion, has a net positive charge. Let's take the element calcium as an example. If the Ca atom is fully intact, with the same number of protons and electrons, it has a neutral charge and is labeled as Calcium I (Ca I). But if one electron is missing, the calcium ion is called Ca II. If two electrons are missing, it is called Ca III and so on. Hydrogen I (H I) would be neutral hydrogen, but because atoms cannot produce any spectral lines when they have lost all of their electrons, and hydrogen only has one, it is merely dubbed H when it is found in a neutral state. Why not do that for all of the other atoms, too? I can perceive another point of anguish for my students' comprehension. * Another gaffe that astronomers made deals with magnitude, the measurement of the brightness of the stars and planets. The ancient Greeks had a subjective, five-step scale from +1 through +6; the more positive the number, the fainter the star. We all know that having 12 of something is greater than having six of the same thing, but in astronomy, a +12th magnitude star is 250 times fainter than a +6th magnitude star. When the Harvard College Observatory photometric (magnitude) scale was adopted worldwide, the intensity difference between a first and a sixth-magnitude star became 100, meaning that the intensity difference between magnitudes was 2.51, the fifth root of 100. Likewise, the scale was extended into the negative numbers for much brighter objects. * Finally, there are the colors of stars. We all know that red is a hot color while blue represents cold. Not in astronomy… Low-temperature stars appear reddish in the night sky, while the hot stars have a decidedly bluish hue, particularly when viewed through a telescope or binoculars. Nothing can be done about that. Thank goodness, red giant stars are big and reddish, while white dwarfs are always small but not necessarily white. * Astronomy is not always this confusing, but the above complaints are some of the difficulties my students face when learning about the evolution of stars. I believe concepts like these which lack some intuitiveness limit the understanding of this very beautiful science. Okay, rant over! Ad Astra!

1427 December 24, 2023: Travels With Jesse: I wanted to share with StarWatch readers some of the images I recorded on my travels to the Mars Desert Research Station and the annular eclipse of October 14, 2023. I have made a temporary switch, except for my astrophotography, in regards to how I record images. For now, I have put aside my Canon 80D digital single-lens reflex camera for the convenience, portability, and multiple camera lenses of a Google Pixel 7 Pro phone. I plan to visit the mirrorless digital cameras as a major upgrade, but for the moment, the 7 Pro images have provided better color rendition, dynamic range, as well as adequate resolution. * My traveling partner on this trip was Jesse Leayman, a former Dieruff High School student I taught in the 1990s. He now works for Pfizer, one of the world's premier biopharmaceutical companies, giving the nod for whether experimental testing of new drugs may continue or should be scrapped. Jesse also coaches swimming for a local YMCA. You'll find him working at the pool from 5 to 8 a.m., about the time that I'm typically going into REM sleep. I'm not acquainted with anyone who knows the human body's chemistry better than he or is willing to share that information with all who inquire. In addition, Jesse is knowledgeable in many other disciplines, including survival skills, astronomy, languages, and music, to name a few. He is a voracious consumer of knowledge, able to synthesize what he learns into practical applications to improve his life and the people with whom he comes into contact. Jesse needs to write a book. * He and I have traveled at least a half-dozen times together, accompanying me as a chaperon on high school astronomy field experiences and personal archaeoastronomy trips to the Southwest. We always end up at Chaco Culture National Historical Park near Nageezi, New Mexico, where he and I have volunteered for the National Park Service. It is a place that I am drawn to as if I lived in that location in a previous life. * On this outing, we first journeyed to Colorado, to visit my friend Joe Smith, who lives at 9200 feet in the Sangre de Cristo Mountains west of Pueblo. If you like scenery, try finding a place with a better view—spectacular. * The Mars Desert Research Station near Hanksville, Utah, was our next stop; our purpose, to help refurbish the two observatories, which include the MDRS Robotic facility that Moravian University has a 25 percent timeshare with the Mars Society. We also observed the annular eclipse there. Then it was onto Utah's Hovenweep National Monument via the Colorado River and Valley of the Gods. Hovenweep is one of the less traveled gems of the National Park Service. Here in the late 1200s, Ancestral Puebloans made one of their last stands against a drying climate before migrating to more reliable water sources. * Finally, it was on to Chaco Culture National Historical Park, the capital of the Chacoan Phenomenon which lasted from about AD 850 to approximately 1300. At Chaco, Native Americans built elaborate structures from stone that served as the epicenter for the worship of thousands, particularly around the time of the solstices. Astronomy and the ability to create a calendar played a central role in their success story. I invite you to journey with Jesse and me as we explored these sacred sites, visited MDRS, and observed the annular eclipse. Go here! Happy Holidays. Ad Astra!

1428 December 31, 2023: Sweet Spot for Quadrantid Meteors: I have only hyped this meteor shower a few times, for it occurs shortly after the celebratory New Year, at nearly the coldest time of the year, and when cloud cover and moonlight can hinder or cancel the show. However this year, I'll take my chances. The Quadrantid Meteor Shower will be at maximum on the evening of January 3 and the morning of the 4th from about 8 p.m. through 2 a.m. * The only time I attempted to witness this display was early in my teaching career when I took several Dieruff astronomy students to Pulpit Rock Astronomical Park near Hamburg, PA. For its time in the mid-70s, and even now, it was a dark site considering its location to neighboring Lehigh Valley, Philadelphia, and New York City. However, we never reached the 1535-foot summit that evening because the dirt road was covered with blowing powder from a snowfall a day or so earlier. We bivouacked at 8 p.m. at the base of the mountain, with skeletal trees swaying in the pumping, numbing winds, throwing our tarps and bedding over the snow. Already shivering, we climbed into our sleeping bags. Within minutes, a gust of wind drove snow over my face and glasses, rendering my view of the sky useless until I wiped the lenses clean. One of my students, Steve Pfenninger, almost simultaneously announced that he had forgotten his gloves and needed to shelter from the cold in his vehicle. Two hours later, we were packing our gear and heading home, freezing and miserable, not the most successful evening outing under the stars. Steve now lives in Switzerland and was Stateside visiting his sister for Thanksgiving. He attended one of my Moravian classes, and we reminisced about that ordeal. By the way, Steve is also a fine artist. His talent graces the covers of the book and lab manual that I had written for my students, the cover exhibiting the last moment of existence of an astronaut as the differential gravitation of a black hole tore him apart. Go below to view it, as well as a map of the Quadrantid radiant. * With a frigid endorsement like that, it is no wonder why the Quadrantids are unpopular with many astronomy enthusiasts. However in 2024, there are some perks. This winter is starting milder than most, so the deep freeze may escape us for a few more weeks. East Coast observers are in one the best locations worldwide for recording the highest activity throughout the entire short, six-hour Quadrantid maximum window which extends to 2 a.m., on January 4. Shower meteors will also be seen after that time. * Rates from dark sky locations can fluctuate from as few as 60 events per hour to as many as 200, considerably more significant than the December Geminids, but their numbers year-to-year are variable. From suburbia, expect to see about 25 Quadrantids each hour. * The radiant, the location from which the meteors will appear to diverge, is circumpolar, meaning it will be visible all night. At midnight, its altitude is about 12 degrees above the horizon in the NNE. During the next four hours, it will circle upward to a comfortable 50 degrees (mid-sky) by 4 a.m. * Although there will be a third-quarter moon in the sky after midnight, quarter phases only produce about 10 percent of the illumination of a full moon. Luna will also have a southerly declination (component) to its location, while Quadrantid shooting stars will diverge upward from the north and northeast. This should easily allow observers to position themselves so that the moon's direct illumination will be shielded from view. * Bundling up in multiple layers of clothing is mandatory. A ground tarp, air mattress, pillow, and sleeping bag rated for cold weather are also essential gear for meteor watching during the winter months. Observe the heavens near the zenith. Any meteor action streaming upward from the north should be from the Quadrantid shower. Much success, and have a blessed New Year. Ad Astra!

Steve L. Pfenninger's pencil drawing, "Chrono-Synclastic Infundibula," graces the front cover of my astronomy book. It depicts the last moment of existence of an astronaut plunging into the abyss of a black hole. Steve was a student of mine at the very beginning of my teaching career.