StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

OCTOBER 2019

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

Print Large Sky Charts For 10 p.m. EDT: NORTH | EAST | SOUTH | WEST | ZENITH

CURRENT MOON PHASES

Current Solar X-rays:

Current Geomagnetic Field:

1207 OCTOBER 6, 2019: Sky Fall: No, this is not about James Bond but about “October Skies,” and it is a sure sign of our move towards chillier weather when the Great Summer Triangle reaches the zenith right after dark. Its three brightest stars, Vega of Lyra the Harp, Altair of Aquila the Eagle, and Deneb of Cygnus the Swan are easily seen, even from the Sky Deck of Moravian’s downtown main campus. The GST will triumph except from the brightest of metropolitan areas. A clear night with brightening moonlight which is happening this week will not hide them either. The most lustrous of the triad is Vega of Lyra the Harp, a blue-white luminary, similar to Sirius the Dog Star, the most brilliant star of the night, but nearly three times Sirius’ distance at 25 light years. Viewing Vega through a telescope makes it look like a dazzling, bluish diamond, consistent with its 18,000-degree F. temperature. The closest star of the GST, however, is Altair of Aquila the Eagle at a mere 16 light years distant and a little cooler than Sirius or Vega. The big surprise, however, is Deneb, the brightest first magnitude star for its 3000 light year distance in the heavens. If bright supergiant Deneb were moved to the standard distance from which the luminosity of stars is measured, 32.6 light years or 10 parsecs, it would outshine the planet Venus over 50 times, creating distinct shadows on the ground from suburban locales. In the northeast, Cassiopeia dominates with its distinct sideways “W-shape” when it is low and “M-shape” when it is higher in the sky. It is really representative of a chair into which the Queen of Ethiopia has been thrown. Two fainter stars, one that completes the front of the seat and the other the crooked back, make for an uncomfortable ride as Cassiopeia ties herself in and is swept upside down on a daily basis. And rightfully so, for she attempted to maintain her power by sacrificing her daughter, Andromeda, to Cetus the Whale (sea monster) in a complicated mythology involving five constellations, also Mercury, Venus, and Neptune, and a kaleidoscope of minor characters, many of which were captured in the 1981 feature film, Clash of the Titans. Andromeda is hanging off the back of Pegasus the Flying Horse, the body of the steed represented by four stars which form a large square tipped on its side as it rises in the east. Below and to the right of Cassiopeia can be found the hero of the story, Perseus, who is returning from what was believed to be a suicide mission to kill the “stoner,” Medusa. He accomplishes that task and rescues Andromeda to boot. He can be seen as a loose aggregate of stars in the shape of an upside down, curly “V” trailing from the crooked back of Cassiopeia’s chair, while Andromeda can be perceived as a group of stars that would have been better named the rear legs of the horse. The stars of Cetus are much fainter and farther south and well below Pegasus, making Cetus difficult to view from suburban skies. Catch them all online here, https://astronomy.org/StarWatch/October/index-10-19.html#10-6-19 or right after dark (8:30 p.m.), and they will be positioned correctly with respect to my description. Ad Astra!

OCTOBER 13, 2019: Twilight and Purple Skies

We have had a number of spectacularly clear days during the past four weeks, and hopefully, these sun-drenched times with their saturated blue skies will continue to add more color and vibrancy to the awakening autumn foliage. Clear, crisp days also can transition into exceedingly transparent nights where the brighter stars near the horizon become visible. My astronomy classes have witnessed this on at least three of the five nights that we have been observing from the Sky Deck of the Collier Hall of Science at Moravian College. In addition, our field experiences to Shooting Star Farm touted the darkest skies to date. Adding to the enjoyment of stars shining against a velvety dark background is the process of just getting there, from sundown through twilight to nighttime. As the sun dips close to the western horizon on very transparent days, look east opposite to where the sun is setting, and you might see what looks like an ominous strip of grey clouds transitioning into a peach color on the top. My first experience with the rising shadow of the Earth in 1975 happened when I was in Arches National Park near Moab, Utah. It was so vivid that I began putting away my observing gear. Clouds were rolling in, I thought, and it was going to be a dismal night. The grey band continued to rise after sunset, becoming more prominent, then began fading as the blue sky opposite to the sun also greyed and blended into the shadow. Eventually, stars began to be seen in the area where the “clouds” had appeared, and I knew that I had been fooled. The rising shadow of the Earth has been a common observation that my students have witnessed this semester. Less common and not as distinct have been crepuscular and anticrepuscular rays, beams of light diverging from the area around sunset (crepuscular) or similar rays converging towards the point opposite to sunset (anticrepuscular). My students have seen both. More common are crepuscular rays diverging from a cloud hiding the sun which is near to or below the horizon. A tall mountain will also cause parallel rays of sunlight to fan outwards from the skyline as they approach the observer, and then converge as they move away towards the antisolar position. Recently, later after sundown when the sky has taken on a hue of deep lapis blue, my students have witnessed the western sky becoming magenta and purple, accented several times by faint crepuscular rays. Fine volcanic dust or dust from forest fires have punched their way into the Earth’s stratosphere. These ultra-small particles filter (scatter) the shorter wavelengths of light creating this spray of magenta and purplish light into the deep twilight sky. Forest fires in the Amazon and Siberia this past summer as well as two major eastern Pacific volcanic eruptions, Raikoke in the Kuril Islands and Ulawun in Papua, New Guinea are most likely responsible for these spectacular sunsets when seen beneath ultra-clean tropospheric air. When my wife and I emerged from the AMC Theaters at the Promenade in Center Valley on Friday, October 4, the sky was putting on a magnificent magenta stratospheric lightshow topped with faint crepuscular rays, helping us to celebrate our 41st year of meeting each other. My smartphone photo can be seen online here, https://astronomy.org/StarWatch/October/index-10-19.html#10-13-19.

A wonderful example of stratospheric dust filtering sunlight and faint crepuscular rays were seen about 30 minutes after sundown on October 4. The lightshow greeted my wife and me as we were celebrating out 41st year of meeting each other. Smartphone photography by Gary A. Becker...

Just eight days later on October 12, and only several hundred yards from where the first picture was taken, another spectacular sunset was witnessed. Smartphone photography by Gary A. Becker...

1209 OCTOBER 20, 2019: Halley's Comet Visible Now!: I nurtured my sky watching by learning the names of the stars and constellations. After all, what could a kid interested in astronomy do while earning only 50 cents a week allowance? That changed to a buck when I reached high school and five dollars a week during college, which included gas money for my daily commutes to Kutztown University. Not to worry, I was basically a happy kid and becoming sky literate at an early age was really a gift which helped me to convey the beauty of the heavens to my future students. One of my astronomical passions was to lay under a canopy of stars during the summer months and just look for those tiny bits of dross entering the Earth’s atmosphere as shooting stars. I quickly learned that some nights were better than others, especially when the Earth entered the debris field of a comet’s orbit. Meteor rates picked up, and because the particles were traveling parallel to each other in their orbits around the sun, they diverged from a small region of the sky called the radiant as they flared in the Earth’s atmosphere, similar to a straight stretch of railroad tracks diverging from a vanishing point as they approach the observer. Those meteors had a common origin associated with a comet that passed near the Earth. A half century ago, the comet that everyone was waiting to see was Halley’s, observed on every apparition since 239 BC, but I had the opportunity of seeing Halley long before it made its appearance in the spring of 1986. That was by watching for the long-released dust from Halley’s tail entering the Earth’s atmosphere, particularly in October. That is what is happening right now and for the next couple of days. The Earth’s orbital path brushes near the orbit of Halley’s Comet. Activity peaks on the morning of Monday, October 21, with meteors radiating from an area above and to the east (left) of Orion’s bright, red supergiant star, Betelgeuse. Hence this event is called the Orionid meteor shower. The moon will be at last quarter near the radiant, which will force observers to view the sky in positions where the moon is blocked, and then trace the meteors back to their vanishing point to identify them as Orionids. As dawn approaches, Orion and the area from which the meteors are radiating will get higher and higher into the sky, so that by 5 a.m. this point reaches its maximum height, about 65 degrees altitude in the south, allowing observers to see shooting stars streaming from above as well as below the radiant. This is when activity should peak at approximately 20 meteors per hour from a rural locale, half that from suburbia. In addition to the Orionids, there are other minor meteor showers that bear mentioning. They are the Northern and the Southern Taurids with meteors emanating from the constellation Taurus the bull. Even combined, these streams produce little activity, but when a Taurid flares, it can be in the form of a slow moving, sparking, wavering, long duration fireball which can be spectacular. In comparison, the normal Orionid meteor is swift and fainter. Remember that if you check out Halley’s Comet in the form of Orionid meteors, clear mid-latitude October nights are not for the fainthearted. When considering your apparel, think winter.

1210 OCTOBER 27, 2019: Stargazing over Moravian: Ever since the third grade, I have been fascinated by the heavens. Throughout it all, I have had to balance that enthusiasm with the fact that I have lived and worked in or near cities with the glow of humanity’s obsession for light transforming the night and dimming the starlight. In 2010, when I first started teaching astronomy at Moravian, the campus and the Lehigh Valley’s light pollution kept my evening students indoors for most of the time. I took classes up to the fifth-floor Collier Sky Deck to view only the brightest objects without the aid of telescopes. Then in 2014/15, I was able to secure donations of quality telescopes, many coming from a Boyertown astronomy enthusiast, David Fisherowski, which sent my program in a whole new direction. The mounting systems which supported the telescopes were computer driven and used the same operating system to control them. In addition, I met John Higbee from northern Virginia, who helped to guide the sale of some of our older equipment, which was outdated enough that it had actually appreciated in value to the degree that other amateur telescope enthusiasts wanted to buy these scopes for restoration purposes. My good friend and former astronomy professor from Kutztown University, Dr. Carlson R. Chambliss, also continued making financial contributions to Moravian which were augmented by generous help from my department chair, Dr. Kelly Krieble, as well as money from the Gerencher Fund set up by my predecessor, Dr. Joseph Gerencher. Good scopes and computer driven mounts made the sky accessible for my city-based astronomy students. When they began making telescopic observations in 2015, the instruments had to be disassembled in my basement lab, transported and reassembled on the fifth-floor rooftop of Collier, aligned to Polaris (the North Star), and calibrated to six additional stars before observations could commence. All of this took time, but when it was done correctly, students with no previous experience could successfully navigate around an urban sky on a good night with only 50 stars visible. They could locate hundreds of objects, bright nebulae and galaxies, double and multiple star systems, planetary nebulae, Uranus, Neptune, and, of course, the brighter planets and the moon. Their telescopes pointed to sky locations where no star could be seen visually, but with the light-gathering advantage of their telescopes, the desired object was revealed. Afterwards, the scopes were returned to my classroom and reassembled again. Student enthusiasm for making authentic observations was obvious and this helped propel my thinking forward. Since the fall of 2018, the Sky Deck has had larger semi-permanent donated telescopes available for students to use. Scopes are no longer disassembled and hauled upstairs, greatly streamlining the process before pupils can begin making observations. See pictures of the Sky Deck and the recent winners in a smart phone astrophotography contest imaging the moon at https://astronomy.org/StarWatch/October/index-10-19.html#10-27-19. Thank you, David, John, Kelly, Joe, and Carlson for promoting astronomy at Moravian College under urban skies. If you would like to try your hand at astrophotography from one of the darkest sites in North America, sign up for Peter K. Detterline’s online course entitled Astrophotography EASC 294 2OL, using the Mars Desert Research Station’s robotic observatory near Hanksville, Utah. Moravian has a 25 percent buy in and owns the larger of the two scopes that students will be operating via the Internet during the half unit curriculum. Research in Astronomy EASC 293 2OL, also taught by Peter, will use the same instrumentation to conduct robotic photometric investigations of variable stars and asteroids.

[October Star Map]

[October Moon Phase Calendar]