StarWatch: Moravian College Astronomy

AUGUST 2021

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

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1302 August 1, 2021: A Great Year for the Perseids: Wednesday morning through Friday morning, August 11-13, will present a wonderful opportunity to view the 2021 Perseid meteor shower. Many astronomy enthusiasts call the Perseids the best shooting star event of the year and for good reason. It combines relatively high rates with warm summer evenings that are relatively short. • Meteor showers are the result of debris released by comets as they orbit the sun. If a comet’s path crosses the plane of Earth’s orbit or comes near to it, an annual meteor shower will most likely be the result. The progenitor of the Perseids is Comet 109P/Swift-Tuttle which last returned to the sun in 1992 and is expected to debut again in 2125. As a result of its many passages around Sol, debris has been spread fairly uniformly across all of its orbital path, enhancing the reliability of the Perseids to produce a consistent showing year after year. • The best advice for observing is not to start too early in the evening. Midnight is a good target time to begin observing because prior to that we are protected by the Earth itself. The analogy is similar to raindrops hitting a vehicle moving through a downpour. The precipitation is preferentially striking the front windshield of your car while the rear window gets only a little rain because it is protected by the automobile. Likewise, in the early evening we are being shielded by the Earth and see reduced meteor activity. As local midnight approaches, the Earth begins to rotate into the meteoroids, allowing it to sweep up more of these particles, resulting in an upsurge of activity. • In the midnight hour some of the colliding Perseids will be skimming the top of the Earth’s atmosphere. These events can create long bright trails, sometimes fireballs, as they are ablated (destroyed) more slowly by the thinner layers of air. • This year, Asia is the favored location for peak rates which can be as high as a meteor per minute for an observer with keen vision viewing from a rural locale. According to the International Meteor Organization, the East Coast sees peak rates occurring between 10 a.m. through 11 p.m. August 12. This means that enhanced meteor activity will most likely happen on both the mornings of August 12 as well as the 13th. • Perseids are easily identified because they will appear to diverge from a vanishing point, similar to how a long, straight stretch of roadway will appear to narrow and converge at some distant location. They will radiate from the top of the upside-down, V-shaped constellation of Perseus. See a map here. Virtually all of the shooting stars that trace back to this region of the sky will be Perseids. • This is the week before maximum; so don’t expect to see many Perseids flying across the heavens, but those that are witnessed will have a tendency to be brighter with more fireballs being spotted before maximum than post-maximum nights. • This was the case for the evenings that I observed the Perseids on the banks of Flathead Lake in northwestern Montana in 2016 and from Guernsey State Park in Wyoming in 2018. I saw brighter meteors on maximum night than on the following evening. Rates also dropped to about half of the activity of the previous night. That again is very consistent with normal Perseid encounters. • Perseid meteor rates will climb steadily this week; just don’t expect to see one every couple of minutes. Observing on August 1, anticipate one or two Perseids in the predawn hours. By August 10, rates should have climbed to 10-15 meteors each hour, if you are in a rural locale. More information about the Perseids will follow in next week’s article. Think clear skies mixed with a couple of bright fireballs!

1303

August 8, 2021: Perseid Meteors “Fly” This Week

It was a meteor that sparked my interest in astronomy, and the Perseids that clinched the deal. This is the week, Wednesday through Thursday, August 11-13, that Perseid meteors will be “flying” in their greatest numbers. Luna, a waxing crescent, sets at 10:08 p.m. on the 11th and an hour later by the 13th. With no moonlight, the rural dark skies of Cherry Springs State Park near Coudersport, PA will glitter with thousands of stars, as well as bright meteors. Even if you live in a suburban locale, you will still see them. Get out that chaise lounge or a folding recliner and face it to the northeast. You’ll probably also want to have a sleeping bag or bedroll, a pillow for comfort, a light tarp in the event of dew, and perhaps a caffeinated beverage to keep you alert. • Right after dark is not the best time to observe meteors, but it may be the only opportunity available depending upon work schedules. Perseids will still be seen, but rates are normally suppressed at this time of the evening because the Earth physically blocks much of the activity. In addition, the radiant, the region of the sky from which the meteors seem to be diverging, is near to the horizon making it impossible to catch the activity taking place below that zone. Regardless of what time you observe, the zenith usually provides the darkest patch of heavens to watch meteors, especially from areas where significant light pollution exists. • The radiant will be close to the NE horizon during the early evening hours and nearly 70 degrees in altitude by 5 a.m. It is located just below the constellation of Cassiopeia the Queen, but within the boundary of the star pattern of Perseus the Hero where these shower meteors receive their name. Any shooting star that can be traced back to this region is most likely a Perseid. • Both of these constellations will be difficult to spot at 10 p.m., but by 1 a.m. they will be much higher in the sky and should be visible even from suburban locations. Cassiopeia will be easier to visualize, partly because of its higher elevation and partly because it has a distinct “W” appearance. Earlier in the evening, Perseus will appear as a sideways “V” opened to the right with the radiant near the vertex of the “V.” A map can be found here. • By 3 a.m. the top of Perseus will be above mid-sky, and you will be catching the meteor action all around the radiant with much higher meteor rates being the result. • Perseids are fast; the dust enters the Earth’s atmosphere at 36.6 miles/second (59 km/s), causing a column of air about a half mile wide to glow as the particle is ablated, vaporized by friction created on the particle by air molecules. • Perseids will also appear to bunch. You might witness two or three in a half minute’s worth of time, then have to wait another five minutes before you see the next shooting star. My record is six Perseids in a 15-second interval. • A Perseid meteor may be visible for only a tenth of a second, a momentary blip on the radar of your eyes. Others will last longer, causing the atmosphere to ionize so completely that the glow of its track will be visible for several seconds after its initial light. These are called “trains” if they last longer than a second and “wakes” if they are shorter. Sometimes you’ll see bright meteors blink from the corner of your eye, and at other times, you’ll see an extremely faint event because you are staring directly at it. You might even witness a “point meteor,” a shooting star coming straight at you from the radiant, a “star” that will appear to brighten slowly, then fade precisely at the location where all of the other meteors appear to be diverging. • But most of all, you will have a memorable experience, and several of the fireballs seen that evening will be etched into your psyche for the rest of your life, instantly available to regale others with the wonderful encounter you had on the night when the Perseids “flew.”

A night with the Perseids was captured in 2020 by Tomas Slovinsky from Slovakia in Poloniny Dark-Sky Park.

1304 August 15, 2021: Unvarnished John Glenn: There has got to be something special about a marine fighter pilot who can survive 190 combat missions and return from each one without a scratch. Was it luck or courage or just being plain good at what he did? And how did Glenn get the machine seat for the first US orbital flight, so important to American prestige during the Cold War that school children today think that Glenn was the first US astronaut to be launched into space? And what was our motive for going into space in the first place? These questions and many more are answered in Jeff Shesol’s Mercury Rising: John Glenn, John Kennedy, and the new Battleground of the Cold War, W.W. Norton & Company, 2021. Shesol’s exhaustive research confirms what was speculated by Neil Armstrong in a June 1973 talk that I attended, that John F. Kennedy was not interested enough in space exploration to make it a national goal, that he had much bigger fish to fry—a slow start to his presidency, nuclear proliferation with the Soviets, and the sticky issue of a divided Berlin. • In the 1960 presidential election, Kennedy had postured himself as pro space mostly because the Eisenhower administration, now championed by Nixon, had been very noncommittal towards it. In what I believe was a bold move, Kennedy chose his chief adversary in the democratic primary contests, Lyndon Johnson, to be his running mate. Johnson wanted the US to commit to a moon landing and took every opportunity to convince his boss to follow his advice. • Johnson’s big break came with the Bay of Pigs fiasco (April 12, 1961) two days after Soviet cosmonaut Yuri Gagarin, the first man in space orbited the Earth. Something had to be done to ignite the public’s spirit, and Kennedy chose a space race with the Soviets that would culminate in a moon landing by the end of the decade. • Meanwhile, the Mercury program was gearing up to send Alan Shepard into space (May 5, 1961). John Glenn was not only the backup for Shepard’s flight but also for Gus Grissom’s Liberty Bell 7 mission which followed on July 21. It was a difficult time for Glenn, the sweetheart of the American space program and the public. The oldest of the astronauts, no one disputed that Glenn worked the hardest and was the favorite of the press. He was referred to as “The Boy Scout,” the moral compass of the Mercury 7 astronauts who all worked hard, but partied hardier. • Shepard’s name was not announced until two days before his Redstone rocket ignited on the launchpad. This caused Glenn more angst during the months of preparation as the press proclaimed that he would be the first to fly. Above all things, John Glenn wanted to be the first human in space. Even when the Soviets beat the Americans to the punch, Glenn continued to lobby NASA officials arguing that he was the most qualified to represent the ethical fiber of the American spirit. • NASA saved the best possible flight for Glenn, the third mission with the new Atlas rocket that finally had the lift capacity to thrust an astronaut into orbital space. Jeff Shesol masterfully builds the tension through the numerous scrubs of Friendship 7, the elation of liftoff (February 20, 1962), and the efforts of NASA to keep Glenn in the dark regarding the possibility that his heat shield was not securely fastened to his capsule. While reading, I found that by the time that Friendship 7 splashed into the Atlantic, east of the Turks and Caicos Islands, I was a nervous wreck, much more so then when at 11, I had experienced the real deal. Lots and lots of backstories make for an enjoyable and informative reading experience and gives a clearer picture of why the US committed itself to a space race and how John Kennedy and John Glenn were an integral part of that initial experience.

1305 August 22, 2021: Prayer in Cairo: I was watching a CNN special on the history of Jerusalem the other night. In that particular segment, the focus was on the Crusades and particularly the struggles of Richard the Lionhearted and Saladin in the Third Crusade. The two basically fought each other in so many bloody conflicts that I had lost count by the end of the program. The inability of each leader to forge a clear victory resulted in the partitioning of the Holy Lands with Jerusalem under the control of Islam while the Christians governed the coast, including the port city of Acre. • In one of the scenes, the French artist Jean-Léon Gérôme’s (1824-1904) painting, Prayer in Cairo (1865) was shown for just a few seconds. At the moment, I knew nothing about the oil on panel image that has a worth in excess of $800,000, but Google solved that issue within short order and also provided me with a wonderful image from a Sotheby’s catalog that can be seen here. It was the serenity and gentleness of evening prayer at the day’s end that caught my attention. And then I saw the thin waxing crescent moon to the left of the second largest minaret in the painting. Did you catch it? • Because of its orientation, I could make a general prediction with regards to the time of the year portrayed in the painting. I am not trying to articulate that Gérôme executed his wonderful painting at this time of the year, but how his work can be interpreted astronomically. • The word crescent means “to have horns.” If the two horns of the moon are bisected and a perpendicular is extended to the horizon, the sun can be located. No matter what the moon’s phase happens to be, Luna’s illuminated portion is always pointing towards the sun. The moon is always within plus or minus five degrees of the sun’s annual trek across the heavens called the ecliptic. • In the late summer and early autumn, the ecliptic is tilted to the horizon at its shallowest angle, causing the moon to gain or lose the minimum amount of altitude on successive nights when it is near to the horizon. Luna rises and sets about the same time for an interval of several days because each day’s orbital motion does not carry the moon very far beneath or above the horizon, allowing it to rise and set about the same time. For our latitude, 40 degrees north, the difference is about 25 minutes. • Gérôme’s Prayer in Cairo is depicted in a near sunset time frame. A distant mosque is seen illuminated by a deeply reddened sun and only the western walls are lit. • Making a rough drawing, I found the angle of the estimated six percent sunlit moon to be inclined to the horizon at an angle of 26.5 degrees. Objects rise and set at an angle of 90 degrees minus the latitude of the location. For Cairo that would be 90 degrees - 30 degrees or a rise and set angle of 60 degrees. The moon’s orbital path is tilted by a maximum angle of plus or minus 28.5 degrees to the celestial equator which rises and sets at an angle of 60 degrees at Cairo. This allows the moon to be tilted at its minimum angle of 60 degrees minus 28.5 degrees or 31.5 degrees. • If Prayer in Cairo represents a fairly accurate portrayal of the sky, then the scene has autumnal characteristics because of the moon’s orientation. Regardless of this astronomy exercise, Gérôme’s Prayer in Cairo is a new favorite of mine, a painting that I would like my students to interpret also. Ad Astra!

1306 August 29, 2021: StarWatch at 25: September marks a milestone, the 25th anniversary of StarWatch. When I began writing the blog in 1996, I was director of the Allentown School District Planetarium which was at that time on a very rocky foundation. The District had tried unsuccessfully to close the facility in 1993 because it did not want to pay the facility’s operating expenses which amounted to about $10,000 per year. Strong public support for the program forced the school board to reconsider, but there was a compromise that I agreed to honor. I had to raise the necessary finances to keep the planetarium in operation. • In the beginning, funding was not an issue with one contributor pledging to donate $2000 each year, a promise which was kept until my retirement. However, I was concerned with what would happen when the initial frenzy of assistance waned. • The Morning Call solved that difficulty, soliciting me to write a weekly astronomy column that would appear daily in the Weather Section of the paper. I named it StarWatch. There was no pay involved, but I realized that each week my name and the ASD Planetarium’s name would appear in print about one million times. Subscribers eventually picked up on that and support for the planetarium grew. • My inaugural StarWatch 0001 appeared in the Sunday, September 2, 1996 issue of the Morning Call. It contained only 86 words. With those constraints it was difficult to say anything meaningful, tell personal stories, or evoke any type of emotional response from my readers. • Progressively over the next several years, I was able to expand the column to a maximum of 330 words. In 2003, StarWatch began running nationally in weekly newspapers that were subscribed to AccessWeather.com, a weather forecasting service. In those days, Access Weather composed the Morning Call’s daily Weather Page. • StarWatch remains the single most important reason why I was able to keep the Planetarium afloat. During those 17 years of financial independence from the Allentown School District, I raised about $170,000 to keep the stars shining for ASD pupils. I’m proud of that accomplishment, the role that StarWatch played in achieving financial stability for my program, and grateful for the opportunities that the Morning Call presented to me. • When I left public education in 2010 with my Moravian College contract firmly in hand, I was writing strictly for Access Weather, and it really wasn’t much fun. I craved a local audience; the Moravian community filled that need. Now with a run of 25 years, which also includes my website, www.astronomy.org, I am hoping that StarWatch will continue to be successful for a few more years. • Besides simply enjoying the creative process, clear and accurate writing allows me to craft better classroom presentations. So I continue on. • My endeavors to pen StarWatch, however, do not represent a singular effort. The greatest solace in the process has been Susan, my wife. She was an English teacher when I met her in 1978. At that juncture of my life, I was editing a national publication called The Reflector, the quarterly newsletter of the Astronomical League. It had a subscription of about 8500 readers. It was a time-consuming endeavor because word processing and online resources still remained years into the future. The typewriter was the most efficient part of the process. Sue quickly assumed responsibilities as assistant editor, correcting my wonky syntax and making me sound much better. We fell in love, and I knew marriage had to be in our futures because we only argued about grammar. Sue continues those efforts today with StarWatch, and I am eternally grateful for her editorial guidance. I figure, if my writing can pass her muster, then it might have a good enough chance of being read by someone else. Thanks so much, Susan. Ad Astra!