StarWatch: Moravian Univerity Astronomy

JULY 2022

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lunar phases

1350 July 3, 2022: Earth Now Farthest from Sun: You are outside on a cool summer's eve with the warming heat from your firepit keeping you comfortable. As the temperature drops, do you move closer to the flames or farther away? Silly question, you might think, but it causes one of the biggest misconceptions that students deal with when thinking about the seasons. Certainly, you will move closer to the flames to soak in more of its radiant heat to feel comfy again, but the sun's distance is not the reason why it gets warmer in the spring and summer. * You can think of the sun as the firepit spewing out radiation in all directions, but it's the angle that this radiation reaches the Earth that is the most critical. If the Earth were flat, then each side of it would always receive the same amount of insolation (energy). Gone would be the harsh environments of the poles and equator and also the ice that is keeping coastal cities from flooding. Moravian University would certainly have surfing as a competitive sport since Bethlehem would be located very near to Pennsylvania's oceanfront. * However, the Earth is not flat despite the cries of the flat-Earthers who live in an intellectually, two-dimensional mindset. It's basically a sphere with the energy of the sun striking its surface at different angles. It's also a tilted sphere with its axis of rotation (spin axis) pointing in the same direction. This means that the angle at which sunlight is absorbed at its surface changes during the course of a year and is at its greatest at summer solstice. * It's a similar situation to being in a fight. I’m a negotiator in reality, but if your situation came to blows, my dad always advised that I should strike my opponent with a direct punch. That would deliver the greatest amount of energy, and hopefully, end the conflict quickly in my favor. * It is that way with the sun and the seasons right now. The Northern Hemisphere is at its greatest distance from Sol, but this is also the time of the year when the sun is highest in the sky (June 21). It's like we are getting a direct punch from a long-armed opponent. It is still going to deliver the most energy; the sun is going to heat up the ground with the greatest efficiency even though the action is being directed from a slightly greater distance. * However, what about the Aussies Down Under, who experience summer when the Earth is actually closer to the sun? Yes, they do get more energy from a star that is nearly three million miles closer to the Earth. Yet the highest temperatures in the world are not found in the Southern Hemisphere. * Take a look at an Earth globe, focusing down on its surface from the North Pole. Then flip it over and look down on the South Pole. You should notice a big difference in the amount of water located in the Northern Hemisphere versus the Southern Hemisphere. The south has more. The heat capacity of water, its ability to absorb energy without undergoing a large temperature change, is truly monumental. The extra energy received in the Southern Hemisphere, due to the sun being closer in the summertime, is mitigated by the energy absorption from the greater amount of sea water which is found there. It is nice to know that continental drift shifted the landmasses northward in our favor. The Earth is at its greatest distance from the sun on July 4. Happy Independence Day, and from the sun as well. A diagram illustrating the seasons can be found here. Ad Astra!

1351

July 10, 2022: The Rat

When I was a Night Sky Interpreter volunteering for the National Parks at Chaco Canyon National Historical Park, near Nageezi, New Mexico, my friend, Jesse Leayman, and I arrived too late to get our beds into our assigned trailer, so we bunked on the floor. Usually on the first night, I have difficulty sleeping in new situations, so I spent several hours awake, hearing the pattering of a mouse going from one end of the trailer to the other. I didn’t think much of it until the following morning when Jesse discovered a large ripped bag of rice that we had purchased the previous day, and "hidden" in a high shelf near the kitchen area. With the hantavirus all the rage in the Southwest, we took extraordinary efforts to secure our food for our four-week stay. The mouse disappeared. That is until I opened my travel bag about a week later to pull out a pair of white socks and hundreds of pieces of rice flew everywhere. It took me about an hour for the vacuum cleaner to suck up all of the kernels, along with a thorough inspection of the contents of my bag, but it appeared as if only the sock was tainted. Once the rice was gone, it seemed as if the mouse really disappeared, but probably not. * Fast forward to just a few weeks ago when Peter Detterline, Ryan Kloss, and I were at the Mars Desert Research Station near Hanksville, Utah. We were at MDRS to get Moravian's robotic telescope in functioning order after two years of dealing with COVID and not being able to travel to Utah to give it a rigorous inspection. That location was chosen by James Cameron, Titanic director, for a futuristic feature film taking place on the Red Planet. Instead the Mars Society with Cameron's blessing acquired the land from the BLM (Bureau of Land Management). * There must be a cornucopia of biological activity happening beneath the two-story tin can-shaped structure because it is much cooler than the desert during the day and critters most likely have some access to water, but I have only had contact with a bat that fluttered down nearly on top of me, literally scaring the (I think you can figure out the next word) out of me. Thank goodness, I was in the bathroom. Pete also killed a jumping tarantula that refused to exit the Habitat, and that's about it for wildlife except for distant coyotes howling at the stars. I have never seen a snake or a scorpion, but I have now witnessed the intelligence of a rat. * Peter discovered it on our first morning that we were there. Actually, what Pete discovered was a gnawed hole in his travel case that went straight through his jacket. We had rat poison on hand, but I quickly found a relocation trap that we set up in front of the stateroom where we thought "he" resided and put a hunk of yummy peanut butter as bait at the triggering point. About eight hours later, the peanut butter was gone, the rat managing to have eaten the food without setting off the mechanism to entrap it. * Emboldened by this act of human trickery, we now began to see him scampering across the wooden upper deck floor. He was small for a rodent, emaciated looking, with a bluish coating of disheveled fur, but he moved very nimbly across the open spaces of the upper deck. Ryan even saw him surveying the room as he scampered across the tops of the kitchen cabinets. * This time we put a large quantity of chocolate-coated peanut M&Ms on the levering mechanism, but the rat evaded us yet another time, going into the trap while we watched, eating a bit of the candy, then quickly exiting without bringing down the door. I even climbed a gray, steel ladder next to the trap where I wanted to drop a plastic water bottle on the door, encasing the rodent before it had any chance to escape, but it wisely never showed. A few hours later, all of the candy had vanished. * In the end, as we left the Habitat with the rat poison dispersed, I felt sad for that wily creature that had evaded the best efforts of three relatively intelligent humans to save its life. Actually, I truly believe that rat is still alive and crafty as ever. Ad Astra!

1352 July 17, 2022: Find Copernicus!: About one week ago, I had the pleasure of volunteering for an evening star party hosted by the Reading Rotary Club, STEM-YEA, and Albright College. It was facilitated by Peter Detterline, who along with me, teaches astronomy at Moravian. Peter handled the first evening, talking about the moon, identifying the lunar seas (maria) and specific craters that could be revealed, some with binoculars and most with a small telescope. The second evening was a scavenger hunt peopled by amateur astronomers from Berks and Lehigh counties. The kids involved were 7th graders, part of a program for underprivileged children from the Reading area. * It had been over a decade since I had worked with 13-year-old students. These kids had an incredible amount of enthusiasm, thanks to Peter's lesson. My group of three guys and one girl wanted to see Copernicus immediately, a 58 mile-in-diameter impact crater, 2.5 miles deep with a central peak (mountain) nearly 4000 feet in altitude. The crater is positioned in an isolated area on the southern edge of the Imbrium Basin. Most of the lunar basins, the darker, circular areas of the moon, were created nearly four billion years ago by asteroids driven sunward by the gravitational pushes of Jupiter and Saturn. Several hundred million years later, these huge and deep depressions gradually filled with molten rock. The lava which created the darker maria had a slightly different composition from the brighter highland regions. * The highlands revealed the history of the moon from the time it formed a crust. The creation of the maria were more recent than the highlands and erased the earliest history of the moon, in a way like icing can cover a damaged area of a cake. The lowlands show the history of the moon from about 3.5 billion years ago to the present. After the period of lava inundation, for all practical purposes, the moon became a geologically dead body except for occasional impacts from meteorites that created craters big and small, but still left the maria relatively smooth and featureless. * This topographical difference makes Copernicus really stand out when it is observed through a telescope under the correct lighting conditions. Rays emanating from the crater, strands of ejecta that gardened the regolith (lunar soil) exposing lighter soil beneath, are easily visible. This is always an indication of a younger age. Apollo 12 astronauts brought back to Earth for analysis some of this ray material thrown from Copernicus. Radiometric dating showed that this soil was only 800 million years old, a recent major impact event in the 4.5-billion-year geologic history of the moon. * "I see it; I see Copernicus!" shouted one of the students upon looking into the eyepiece of my refractor for the first time. The scavenger hunt was in full swing. * My eyepiece had a reticle (crosshair) etched into the glass. It also was equipped with a hand controller/computer to move the telescope across the lunar surface. The buttons were positioned in a similar fashion to a computer game, giving the participants of my group instant familiarity with the positioning attributes of my mount, gliding the telescope around to pinpoint the Sea of Crisis and the Sea of Tranquility, where Neil Armstrong put humanity's first footprint on the lunar surface. They found Copernicus in a flash and a few other craters too. The crosshair zeroed in on the location, and because the telescope had a drive system which followed the moon, the reticle remained fixed at that spot so that the pupil's positioning could be verified by me. My four 7th graders hit the mark precisely about 80 percent of the time which was a tribute to Pete's orientation lessons. It was an evening of fun and camaraderie as our group shared our love of astronomy to a group of impressionable teens who were interested, animated, and wanted to learn. Ad Astra!

1353 July 24, 2022: Delta Aquarids This Week!: Late July and August signals a pronounced increase of meteor activity which coincides nicely with our desire to spend more time out-of-doors. I have lots of fond memories of camping during these warmer months. My friends and I would specifically choose a dark location to view shooting stars, often in New Hampshire where we would stay at the Jefferson (NH) Camp Grounds. The evening hours before midnight were literally a hoot. A bright shooting star would flash across the sky, and pockets of cheers and screams from observant campers would echo against the black dome of the Milky Way-filled sky. Gradually as the hours ticked away, the campground hoopla would slowly fade, so that by 1 a.m., it was normally just my friends and I who were still watching. We would usually recline in silent competition updating each other when a bright meteor was seen. * The nights were always very dewy, just like in our area, so plastic coverings over our sleeping bags and air mattresses, as well as a ground tarp, were a necessity; and if we were imaging the sky for shooting stars, some type of battery operated, dew-busting heater around the lens was mandated. Lately, I have used a battery-operated fan to produce airflow around the lens to alleviate the dew. Chemical hand warmers attached to the camera lens with rubber bands could also serve as a lightweight solution for dew removal. A tripod and a cable release or intervalometer may also be necessary. * Unfortunately, the biggest meteor shower of the summer, the August Perseids, will be highly curtailed this year by a full moon that coincides perfectly with the best nights of observing. By the end of July, during new moon week, however, there will be at least five minor streams that are active, in addition to the Perseids, which are just beginning to heat up. The best of the lot is the Delta Aquarid Meteor Shower which reaches its maximum on the morning of July 29, producing about 15 to 20 meteors per hour from a rural locale. The moon is new on the 28th. From suburbia, the rates will be more like five meteors per hour, radiating from the SSE to south around 3 a.m. to dawn. You will lose some sleep over this meteor event. * The radiant, the location in the sky from where these meteors will appear to diverge, is positioned to the right of the center of a triangle created by Jupiter (left), Saturn (right) and Fomalhaut (below). View the map which can be seen here. That position is slightly to right of Delta Aquarii, the star which lends its name to this meteor event. Early Perseids can be viewed too! This meteor shower has a reputation for producing memorable fireballs, generally radiating from high in the sky, catching observers off guard if they are viewing the heavens in the south. More about spotting a few Perseid meteors next week before the moon interferes. For now, good Delta Aquarid hunting. Ad Astra!

1354 July 31, 2022: This Year's Perseids Dulled by Moonlight: Thursday morning, August 11, through Saturday morning, August 13, are the best nights for the 2022 annual Perseid meteor shower; however, this year the Perseids are dulled by a nearly full moon. If you want to see Perseids in a dark sky, you will have to watch for them from now through August 8 after midnight. * It was the Perseids that got me started into observational astronomy at the age of 14, when my cousin John and I discussed for months how we were going to view them. He and his family lived north of Allentown, PA where in the mid-60's the sky was pleasantly dark on a clear evening. Just hours prior to the big night, a sultry summer day was capped off with a strong thunderstorm that rolled through the region during the late afternoon, but the sky cleared quickly, leaving the night dark and transparent. To a 14-year-old kid eager to spot meteors, it was as if a miracle had just occurred. I can still remember one particularly vibrant Perseid that scorched the heavens around 3 a.m., leaving in its wake a fading ionization afterglow of its path for about 10 seconds. Man, I was hooked on sky watching from that moment forward. * The best advice for any Perseid observer is not to start viewing too early in the evening. That's because your location on the Earth is in a poor place to see many meteors. The analogy is similar to being in a vehicle moving through a downpour. It is the front windshield that seems to be getting all the raindrops as you plow through the deluge. The back window only gets a scattering of droplets because it is protected by the front of the car. Likewise in the early evening hours, we are being sheltered by the Earth because our position is analogous to watching meteors from a car's rear window, reducing activity. As local midnight approaches, the Earth slowly makes its rotational debut into the meteoroids, bringing us to the front window with a resulting increase in activity. * This year, it is the morning of Saturday, August 13, when peak activity should be taking place, but a fat waning gibbous moon will be in the sky from early evening until past sunrise. If you are still planning to observe at that time, keep the moon away from your field of view so that your vision remains unaffected by its light. The highest Perseid rates that I have ever experienced on a moonless night were about one meteor per minute from a dark Wyoming location; however, these shooting stars have the tendency to bunch with several events happening within a short interval of time, followed by a period as long as 10 minutes where no activity occurs. Moonlight should prevent that from materializing this year. * A better suggestion might be to watch after midnight during the first week in August. I have seen Perseids as early as July 29 when I was on the hunt for Delta Aquarid meteors. See last week's StarWatch here. They are generally brighter before the date of maximum activity and fainter after that time. You will not see many Perseids, but some of them could be really spectacular. * From suburban locales the zenith is your best bet for the darkest skies. It is also important to keep the moon away from your direct field of vision. Face towards the NE after midnight. Perseids will be radiating from a point low in the NE at midnight and about mid-sky in the east by dawn. There are many other minor meteor streams active during this time period, so you will definitely see meteors, but probably most of them will not be Perseids. Next year, the Perseids will rule with a new moon occurring near the time of maximum activity. Can't wait… Ad Astra!