StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

AUGUST 2018

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

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1146 AUGUST 5, 2018: Perseids: The Big Show Begins: From Saturday evening into Monday morning, August 11-13 are the big nights for the 2018 Perseid meteor shower. Many astronomy enthusiasts call the Perseids the best shooting star event of its kind during the year, and that may be true because it combines relatively high meteor rates with warm summer nights which are relatively short. Compare that to the Geminids in December, where the number of meteors each hour could be double the Perseids, but the temperature may very well be in the teens. By dawn if you do not succumb to the cold, all you can think about is a hot shower. No sleeping bag or bags, handwarmers, or hot drinks have ever kept me warm for very long during the Geminids. The best advice for Perseid meteor observing is not to start too early in the evening, although this year may be an exception. The analogy is similar to being in a vehicle moving through a downpour. It is the front window that seems to be getting all of the action as you plow through the deluge. The back window only gets a drop or two because it is shielded by the front of the car. Likewise, in the early evening we are being shielded by the Earth and normally see reduced meteor activity. As local midnight approaches, the Earth slowly makes its rotational turn into the meteoroids, bringing us to the front window, with the resultant increase in activity. If the peak rates of the shower coincide with the post-midnight hours, observers could be treated to even more enhanced action. That could happen for this year’s Perseids, but currently Europe is in the most favored locale. The 2018 peak according to the International Meteor Organization occurs between 4 p.m. August 12 through 2 a.m. August 13, EDT which means that meteor activity could be somewhat enhanced on the evening of the 12th before midnight if maximum activity occurs nearer to the middle of this time interval. As we begin to rotate into the debris dislodged from the many passages around the sun of Comet 109P/Swift-Tuttle, some of the first Perseids witnessed are just skimming the top of the Earth’s atmosphere. They can create long bright trails, sometimes fireballs, as they are ablated more slowly by this thinner region of air. A much earlier peak also means that rates may be enhanced on the previous morning, Saturday into Sunday, August 11-12, but more towards dawn than midnight. This is what the American Meteor Society is predicting. If the highest meteor rates are encountered closer to the predicted end time or even beyond, more enhanced rates can be expected on the morning of August 13. Predicting a meteor shower peak is still not an exact science, but the Perseids have been known to show a certain amount of consistency over recent years. Do not fret, however, if the weather looks like it is going to bomb out for the best nights. This week, leading up to Perseid maximum, will yield many beautiful shooting stars with more fireballs being spotted on pre-maximum evenings than post-maximum nights. Observing the Perseid meteor shower for two nights on the banks of Flathead Lake in northwestern Montana in 2016, Pete Detterline and 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 climb steadily the week before the time of greatest activity and drop off rapidly afterwards, so you’ll still have plenty of opportunities to snag meteors in the upcoming days. More information about the Perseids will follow in the next article or read ahead at http://www.astronomy.org/StarWatch/August/index-8-18.html.

1147 AUGUST 12, 2018: Night of the Perseids: This is the weekend (August 11-13) that Perseid meteors “fly,” and they will do so against the backdrop of the summer Milky Way. With the moon being virtually new, the rural dark skies of Cherry Springs State Park near Coudersport, PA or Guernsey State Park in eastern Wyoming will glitter with thousands of stars, as well as bright meteors. Get out the chaise lounge or that folding recliner that you bought from L.L. Bean, a sleeping bag or bedroll, a pillow for comfort, a light tarp in case of dew, and perhaps a caffeinated beverage. Right after dark is not the best time to observe meteors, but it may be the only opportunity available depending upon your schedule. Perseids will still be seen, but rates are suppressed at this time of the evening because our location on Earth physically blocks much of the activity. Although the radiant, the region of the sky from which the meteors seem to originate, is above the horizon, we do not catch any of the activity which is happening below this point because of the obstructions that trees, buildings, and the horizon provide. Face your recliners towards the NE, and observe the area of the sky which is overhead. In any locale where there is light pollution, the zenith usually provides the darkest patch of heavens to watch. Perseids will seem to spray outward from a vanishing point in the NE, close to the horizon during early evening hours and high in the east by dawn. The effect is analogous to standing on a long stretch of railroad tracks. The rails approach and pass you on either side, appearing to diverge from a distant vanishing point, even though you know that they must be parallel to each other in order for a train to navigate them successfully. Likewise Perseid meteoroids, the tiny bits and pieces of silicate dross released by Comet 109P/Swift-Tuttle, are moving parallel to each other as they orbit Sol. Just like the railroad tracks, these meteors will appear to diverge from a vanishing point, called the radiant, as they approach you. The radiant is below the constellation of Cassiopeia the Queen and just above the head of Perseus the Hero. Any shooting star that can be traced back to this region is most likely a Perseid. Both of these constellations may be difficult to spot at 10 p.m., but by 1 a.m. they will be much higher 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 sideways “W” appearance (90 degrees counterclockwise by morning) in the heavens. Perseus will have a triangularly shaped top (his head) which will spread outward, its lines curling at the end for his winged feet. A map and photograph are online at http://astronomy.org/StarWatch/August/index-8-18.html to help you to visualize their shapes better and access a more precise location of the radiant. By 3 a.m. the top of Perseus will be above mid-sky, and you will be catching the action all around the radiant. Meteor rates will be much higher. Perseids are fast; the dust enters the Earth’s atmosphere at 36 miles/second, causing a column of air about a half mile wide to glow as the particle is ablated, vaporized by the air itself. 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. 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 looking directly at it. You might even see 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 converging. I’ve had that experience about a dozen times in my life. 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.”

1148 AUGUST 19, 2018: Guernsey Meteor Madness: This year’s trip to the Mars Desert Research Station to get the MDRS Robotic Observatory online and then to volunteer at Guernsey State Park in eastern Wyoming to view the Perseid meteor shower proved very successful. At MDRS, Moravian College owns the telescope and mount, as well as a 25 percent timeshare of the robotic observatory’s use. This StarWatch will deal with the Guernsey event, while the next several StarWatch articles will tout the accomplishments at MDRS near Hanksville, Utah. The Wyoming Park Service invited us back after Peter Detterline and I worked with Guernsey officials last year to promote the total solar eclipse of August 21, 2017. Jacob Wetzel, a former spring 2018 Moravian astronomy student of mine, and Drexel University graduate in filmmaking, also accompanied us as photographer and videographer. In the past I have volunteered for a number of state and national parks across the country, and they all have had their quirks; but not Guernsey. Under the capable leadership of superintendent, Todd Stevenson and his assistant Chris Delay, the park is managed under a spirit of eco-friendliness and a genuine desire to promote its natural resources. Their leadership style advocates the unique capabilities of their employees and brings out the very best they have to offer, creating a spirit of camaraderie and cooperativeness. Everyone could learn from Todd’s and Chris’s management style. Besides the programming and evening star watch activities planned for the public, we hoped to view lots of Perseid meteors, and we were not disappointed. The Perseids are a product of the dross released from Comet 109P/Swift-Tuttle, which last rounded the sun in 1992. Perseid meteors result from this cometary debris as Earth intersects its orbit, and they radiate from a location near the top of the constellation of Perseus the Hero, hence the name, Perseid meteors. What makes this occurrence so special is that these meteors “fly” during the warm month of August when conditions are optimal for their observation and lots of people are on vacation, especially camping; but their rates do fluctuate from year to year and so do their brightnesses, depending upon which strand of debris the Earth encounters. This year, the numbers were consistent with expected rates, but the Perseid meteors seemed to be less bright, hence a dark location like Guernsey proved optimal. As an example, I saw no fireballs during our four nights of observations, but we did witness a dramatic increase in Perseid activity during the mornings of August 10, 11, and 12. There was some controversy this year as to whether the highlight evening over the US would occur on the morning of the 12th or 13th or broadly encompass both days. During a period of four consecutive nights, I recorded a total of 341 meteors, 265 Perseids and 76 non-Perseid meteors. The non-Perseid events will be called sporadic meteors, even though many of these were actually related to smaller, organized, comet-induced streams of shooting stars entering the Earth’s atmosphere. Although the beginning and ending times of my observations varied from night to night, I was always observing between the hours of 1:30 a.m. and 4:30 a.m., Mountain Daylight Time. Throughout these 3-hour intervals, sky conditions remained remarkably consistent during the four nights. Here are my results for the following mornings: August 10—24 Perseids, 14 sporadic meteors; August 11—43 Perseids, 12 sporadic meteors; August 12—76 Perseids, 21 sporadic meteors; and August 13—79 Perseids, 18 sporadic meteors. The broad maximum over the mornings of August 12 and 13 probably resulted because of our geographical location being midway between the position of maximum activity. One thing is definite; four nights of observations with days of limited sleep can certainly take its toll because of public presentations, conversations, and cool, windy, and dry observing conditions. The three members of our group all had the sniffles or sore throats by the time we left Guernsey. We’re all well now with fond memories of our Wyoming Perseid experience and anticipate future visits.

1149 AUGUST 26, 2018: It's Just Another Day on Mars: Little water, no refrigeration, no solar power, and the gasoline-driven backup generator just quit with a large puff of vaporized coolant pumping into the hot desert air… Alright, I should have realized that there might be problems upon arriving at the Mars Desert Research Station near Hanksville, Utah. When I opened my “stateroom” door, I discovered the mirror had fallen and cracked in about a hundred places. There were small chards of specular glass scattered across the floor. I’m not superstitious, but hey, isn’t seven years of bad luck just a little extreme? Where’s the salt over my right shoulder? I couldn’t find any. I admire Peter K. Detterline’s attitude. He is the lead astronomer and visionary for the Mars Desert Research Station Robotic Observatory. Moravian has a 25 percent telescope timeshare in this endeavor, and Pete is gearing up to teach an on-line astronomy course about observational techniques this fall. When trouble arises, Pete says, “It’s just another day on Mars,” and in a realistic way it could be much worse. If we were on ruddy Mars, now shining brightly low in the south around 11 p.m., we’d have to suit up before going outside to fix some of these problems; whereas at MDRS all we have to do is open the hatch. On an even brighter note, the sun pushed temperatures into the low 100s on this August 1 day, but the robotic observatory seemed to be functioning properly with the clamshell dome opening and closing remotely and the cooling fans of the cameras humming and whirling confidently. That was before the power loss, but we brought everything back online again this morning. There may be a moral to this story as I contemplate taking off my sweaty T-shirt and replacing it with the one that I previously thought was dirty enough for cleaning. Let’s not screw up humanity’s accomplishments with another conflict that will set us back to Neolithic times. I only want to collect stone implements, not use them. Life for us is tough enough even with the amenities which most of the world’s population still find in scarcity. On that first night, we slept outside, Pete in a hammock and I in a foldout contraption that got me horizontal and above ground but was very uncomfortable. I still managed to sleep. Next to me in the same type of foldout was our photographer/videographer, Jacob Wetzel, my top Moravian astronomy student from this past spring who wanted to join our group. I really wondered what he was thinking while all of this was unfolding, especially when I promised he could accompany us on our “luxury” astronomy refit to Utah this summer. Once Jacob’s head hit the cot, however, he was in dreamland. When I awoke around midnight, the moon was up, and ruddy Mars was shining brightly in the south. Two hours later, still conscious and now getting cold, I popped back into the habitat and finished the night in my bed, a little uncomfortable because of the heat, but okay enough to sleep. Jacob made it through the whole night in the cot. The next morning, things did take a turn for the better. With the sun now shining, the solar power returned, but the system was not charging. We checked the fluid levels and tested the backup power generator. It started, and then ran continuously for the next six days. There are support people from the Mars Society on call when problems arise, and they respond quickly with good advice. We also managed to get the swamp box operational, an evaporative device that circulates air through a moist, water-absorbing material, cooling the habitat’s interior by at least 20 degrees Fahrenheit. It works exceptionally well in low humidity areas like deserts, and is similar to the way you feel after emerging from a swimming pool on a windy, summer afternoon. Good days, bad days… As I am writing this, the power just went off again, but we now know the reason why this time. In the end we will be successful, but it may take a couple of days before we are totally back on track. Meanwhile, Moravian’s robotic observatory is looking good. More adventures at MDRS next week…

[August Star Map]

[August Moon Phase Calendar]