StarWatch: Moravian College Astronomy

APRIL 2017

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lunar phases

1076 APRIL 2, 2017: Mercury This Week: Last week, I spoke about the smiley moon, a condition that occurs during the spring months of each year, February through May, when the thin horned moon seen in the western sky after sundown appears to change position at a steep angle to the western horizon from night to night. The bow of the crescent, which points to the sun’s position below the horizon, is nearly parallel to the horizon creating the mouth of the smile. Imagination is necessary for the eyes. The steep angle of the ecliptic, the plane of the Earth’s orbit projected into space, also affects the positions of the planets to the horizon causing their orbits to be inclined to the landscape at a steep angle. Currently, the most elusive of the naked eye planets, Mercury, is benefiting from this condition. During the past several weeks, the Messenger God, moving in a counterclockwise direction, has swung around the back of the sun, becoming visible in the western sky about 45 minutes after sundown. On April Fools Day it reaches its greatest eastern elongation which for this apparition is a measly 19 degrees from the sun. Mercury can be as far away as 28 degrees from Sol, so at this elongation, we are viewing Mercury when it is near to its closest distance from the sun. Nineteen degrees is not a large angle to be positioned away from the sun, but when that distance is on an orbital path that is tipped about 70 degrees to the horizon, it is distant enough to be easily seen after sundown. In addition, the Earth’s rotation will take nearly 90 minutes before Mercury sets providing enough time to view the smallest planet in a nearly dark sky. You’ll need a good western horizon. Be at your observing location about 40 minutes after sundown. Mercury will still be at a comfortable altitude of 10 degrees; that is equivalent to a fist held at arm’s length, thumb on top, bottom of the fist on the horizon. Use binoculars to scan the area above the horizon which has the greatest glow. If you pick up a starlike object, it will be Mercury. However, during this week Mercury starts sliding back towards the sun, and its brightness decreases by about three times. Much success!

1077 APRIL 9, 2017: The Glass Universe: I recommend reading Dava Sobel’s The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars, Viking, 2016, as a sobering and scholarly work about how the women calculators of Harvard Observatory influenced and guided early 20th century research in astronomy. They were called “Pickering’s Harem,” and for a long time, I felt as if they were more of an ornament to the routine of the observatory, when in fact, these women were its soul. Edward Pickering, director of the cash-strapped facility between 1877 and 1919, at a time when it was divorced from Harvard’s money, encouraged the hiring of talented women calculators for many reasons. They were paid less than their male contemporaries, but they were also meticulous in their work habits, even-tempered, and were willing to embrace with enthusiasm the mundane tasks of reducing the information gleaned on the hundreds of thousands of photographic glass plates taken in Cambridge and Arequipa, Peru. This was accelerated in no small part by two great benefactors of the fledgling Harvard facility, wealthy New York heiresses, Anna Palmer Draper and Catherine Wolfe Bruce, who kept the wheels greased by contributing yearly stipends to Pickering, while encouraging him to continue hiring women to augment his staff. Sobel, however, does not cast Pickering in any disparaging light, considering him well ahead of his time with regards to women’s rights, nurturing their efforts, and championing their successes to the worldwide astronomical community. And contribute they did! Our magnitude system for quantifying the brightnesses of stars resulted from the work of Harvard’s female calculators. Annie Jump Cannon and Antonia Maury created the majority of the system in use today to classify stars. Cannon ordered the spectra of stars via a temperature sequence, OBAFGKM, hot to cool, and Maury understood that similar spectral classifications could yield dissimilar luminosities, i.e., red giants (bright) and red dwarfs (faint), as examples. Finally, Henrietta Leavitt discovered the period-luminosity relationship of classical Cepheid variables, providing her male contemporaries with the ammunition to prove that the Milky Way was just one of many galaxies in our cosmos. The Glass Universe is well worth reading to understand the complexities and triumphs of women astronomers working only one century ago.

1078 APRIL 16, 2017: Robotic Observatory Becoming a Reality: Moravian College Astronomy’s buy-in for a 25 percent usage of a new robotic observatory being constructed at the Mars Desert Research Station near Hanksville, Utah is becoming a reality. The foundation and pier for the structure were poured this past week. All components for the facility have been purchased. Assembly and testing of the MDRS Robotic Observatory will be occurring during June and early July of 2017. The bulk of the facility was made possible through a $50,000 gift to the Mars Society, but funding was insufficient to make the observatory fully robotic or capable of conducting research unless onsite. As a member of the astronomy team of MDRS, I was participating in the planning of this sky watching station, and I had an idea. During late spring of 2014, I was beginning to refurbish the Sky Deck on the rooftop of the Collier Hall of Science. New instrumentation was part of that goal, and a steady flow of money into the MoCo astronomy program was being accumulated through public donations. Enter Boyertown astronomy enthusiast, David Fisherowski, who began gifting quality used telescopes and mounting systems to our astronomy program, and it became obvious to me that Moravian had within its grasp, the ability of promoting a robotic astronomical research facility in one of the darkest regions of the US as well as accomplishing with a small delay, the goals of revamping the Sky Deck. MoCo Astronomy will remit a check to the Mars Society for $20,000 in the next several weeks to make the MDRS Observatory robotic and research capable. The final piece of the puzzle has been my recent acquaintance with John Higbee, a resident of northern Virginia, who restores older astronomical instrumentation. Our existing cadre of telescopes will not be “junked,” but hopefully sold to other enthusiasts who are interested in refurbishment. That should be sufficient to supply the additional capital to spur the modernization of the Sky Deck in a timelier manner. If someone would have told me that this is where we would be when Dave Fisherowski made his first donation to Moravian in early June of 2014, I would have laughed. Not so anymore. A great summer of discovery and observing lies ahead!

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APRIL 23, 2017: Robotic Observatory Is Concrete

The astronomy team of the Mars Desert Research Station near Hanksville, Utah, of which I am a member, received confirmation this week that the concrete pad for the MDRS Robotic Observatory has been poured. Photos can be seen at http://astronomy.org/StarWatch/April/index-4-17.html#4-23-17. In addition, a check for $20,000 from the Moravian College Astronomy Account, raised through public donations, should be on its way to The Mars Society to secure Moravian’s 25 percent vested share of the telescope’s time. Actually, I should say telescopes’ time. As discussions evolved pertaining to the use of the facility (research and astrophotography), it became obvious that the two were incompatible using one instrument. The larger of the two telescopes, a 0.36 meter (14-inch), F/10, Celestron EdgeHD, Schmidt-Cassegrain reflector named the Moravian Telescope, will be used for research. This instrument produces a relatively high magnification making its field of view small, but allowing the image scale to be larger which will show a greater amount of detail. The image scale relegates sensor parameters, such as the size of the pixels which will record the data. All of these considerations would not allow an all-in-one instrument to complete the task of research as well as astrophotography. Enter David Fisherowski, who has seeded Moravian College with several fine telescopes and mounting systems. He donated to the project a high-end Stellarvue, F/6, apochromatic (three element) refractor which is particularly well-designed for astrophotography. It will produce a smaller image scale several degrees across, perfect for producing beautiful starscapes. The two telescopes will be mounted side-by-side rather than in a more traditional piggyback arrangement to reduce stresses on the Moravian instrument. This will greatly improve its pointing accuracy. Another feature of the MDRS Robotic Observatory and Moravian Telescope is that sensors will have to determine that meteorological conditions are conducive for observing. Clouds and wind must be monitored automatically so that the equipment is not mistakenly subjected to destructive forces or precipitation. After a night of observing, a clamshell-type dome will close automatically, and a cover will be deployed over the front of the Moravian Telescope to keep its corrector plate clean. It’s been an interesting learning curve to design the MDRS Robotic Observatory, but everything is coming together nicely.

Are we there yet? Every project has to have a beginning and for the MDRS Robotic Observatory near Hanksville, Utah, that means the pouring of the foundation for the observatory and the pier support for the mounting system. The mount supporting the two telescopes will be placed on the round concrete plug in the center which goes below the frost line to enhance stability, and is separate from the pad to minimize vibrations in the system. Rebar was used to strengthen the pad from shifting and cracking due to porous soil conditions at the site. Once the metal forming the circular pad is removed, the area will be backfilled so that the soil level will be equal to the pad height. Photography by Curtis Whipple, general contractor, Hanksville, Utah...

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APRIL 30, 2017: Big Dipper Riding High

We have had a really crazy spring with mostly cloudy evenings sprinkled with a few spectacular nights. If we get clear skies in the next week or so before moonlight blasts away the stars, take a moment to become familiar with the Big Dipper. During late April and throughout May, it appears right after dark at the top of the northern sky, upside down, shining with distinction even from urban locales. The most famous star pattern to Americans is not even a constellation. The Big Dipper represents the brightest stars of Ursa Major, the Great Bear, a constellation that can only be seen in its full splendor from rural locations. Witnessed from suburban and more urban places like the Lehigh Valley, it’s simply the Dipper, three stars that represent its handle, the tail of the bear, and four luminaries for its cup, the bear’s body. What is interesting about most of the Big Dipper is that its stars belong to a small star cluster that appears huge in the sky because of its closeness to us. Other members include Gemma of Corona Borealis (Northern Crown), Beta Aurigae (Charioteer), and Delta Aquarii (Water Bearer), among another three dozen luminaries. The Ursa Major cluster may even include the brightest luminary of the night, Sirius, the Dog Star, although a recent study indicates that Sirius may be too young to be a member of the group. In the Dipper only the two end stars, Dubhe on the left and Alkaid on the right, are not part of the Ursa Major cluster. When viewed with binoculars, the end stars can be seen to have different colors compared to the cluster stars, yellow-orange for Dubhe and a bluer color for Alkaid. The five Dipper stars that are part of the cluster are 78 to 81 light years away, while Dubhe (left) is 124 and Alkaid (right), 101 light years distant, respectively. The cluster stars were all “born” about the same time with approximately similar masses, and are therefore, shining with similar blue white colors. If you want a good test of your eyesight, look at Mizar, the middle luminary in the Dipper’s handle. Alcor, a fainter star, is about 1/5-degree (12 minutes of arc) away from Mizar. Alcor is revolving around Mizar with an unknown orbital period. But there is more. A small telescope at 50 power will separate Mizar easily into two stars that look and are identical. Each of the stars of the Mizar binary, including Alcor, is yet again a double, making the Mizar-Alcor system a sextuplet. Confused? Me too!