StarWatch: Moravian College Astronomy

JUNE 2021

JUNE 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 Solar X-rays:

Current Geomagnetic Field:

lunar phases

1294 June 6, 2021: Safe Solar Eclipse Observing—June 10: On Thursday, June 10, my birthday, the sun will rise along the northern mid-Atlantic, New England, and northern mid-Western states partially eclipsed by the moon. Along a rather wide band starting north of Thunder Bay, Ontario, Canada, eastern Hudson Bay and almost all of James Bay, most of Baffin Island, extreme northwestern Greenland, the North Pole, and ending in northeastern Siberia, Russia, this eclipse is annular (ringed), meaning that the entire silhouetted disk of the moon will be seen against the bright sun; the moon too small—too far from the Earth to cover the sun completely. • Locally, about 75 percent of the sun’s disk will be obscured by the moon at sunrise which could produce some interesting visual effects as the sun approaches the horizon. See last week’s StarWatch. The challenge for June 10 is how do you observe the sun safely? • The solar glasses that you may have purchased for the 2017 eclipse are your best bet. If the Mylar or black film material is still in good shape—no scratches—then you have in your possession all that you need to view this event. If you want to purchase glasses, I would suggest immediately ordering a pair from Rainbow Symphony. Its website can be found here. • If you did not purchase solar glasses, all is not lost. Go to a welding supply store or Google welders shades (no apostrophe) and purchase a number 13 and a number 14 welders’ shade. A number 14 shade is good for viewing the sun when it is higher in the sky or at sunrise, if the sky is crystal clear, while a number 13 works well if there is haze near the horizon. Welders’ filters are additive, so if a number 14 filter is not available, the purchase of two number seven filters will do the trick. Regular welders’ shades give you a green image of the sun while “gold” coated filters produce an orangey view. The gold shades are more expensive. • If you own a small telescope, spotting scope or binoculars, you can project the image of the sun through an eyepiece. Since the sun is a dangerous star to observe without filtration, observers should never locate Sol by looking through the instrument. Have someone hold a white piece of cardboard in back of the eyepiece and allow the rising sun to cast a shadow of your equipment onto the board. Manipulate the barrel of your scope or binoculars so that it is pointing towards the sun and producing the smallest possible shadow on the whiteboard. The instrument will then be projecting the sun’s image. The white cardboard can be used as the projection screen. This technique is actually easier than it sounds, but I would strongly suggest practicing before E-day. Make sure that if kids are involved, the finder scope on your telescope or spotter is covered, and an adult is always officiating. Do not expose your equipment to excessive heat buildup by projecting the sun for long periods of time. Even easier techniques, such as building a simple solar projection box, can be found on my website, astronomy.org. I also recommend listening to my Moravian College class video on observing techniques for solar eclipses which is located here. • Think clear and sunny for Thursday, June 10. My 95-year-old mother, Elsie, says that it has never rained on my birthday. I’m holding her accountable to that statement. Clouds be gone too…! Ad Astra!

1295

June 13, 2021: The Sun Can't Hide Forever

I really hate mornings, but when an astronomical event like a solar eclipse is going to take place, I have to let my better angels guide my actions. The devil, however, was right on cue as I lay sleepless in bed at 3:15 a.m. with the alarm set to jangle me awake just 75 minutes later. Whispering in my ear, he cajoled me into thinking that it would be alright to turn off the alarm, to let my internal clock wake me. “You’ll be so cranky today, tired, and lifeless, but think about how you will feel if you get an adequate amount of sleep. You’ll be rested and so much happier on your birthday.” • I renounce the devil each Saturday in church, but the feeling of reluctance has persisted for most of my life when dealing with sunrise events. I’m just not a morning person. So I got up, dressed, and was on the road in about 15 minutes, leaving the devil’s enticements behind. • My observing location is about four miles northwest of where I live, a beautiful grassy hilltop with excellent horizons surrounding it. I have been using it for almost 20 years, particularly in the winter for photographing the planets that are near the horizon. I had met the nephew of the field’s owner, perhaps as far back as 15 years ago while imaging planets. His girlfriend at that time had been a former Penn State student of mine. We had a little reunion on the field when she joined us and that helped solidify my acceptance to use that location for astrophotography. • Today, however, the grass had not been cut, so it was a little intimidating driving blindly off the road into three-foot swaying stalks. In about 10 minutes my equipment, tripod, camera, intervalometer and filters, were ready to image, but it was evident from the layers of clouds on the horizon that the sun would rise decidedly subdued. That was actually an advantage because I would be able to photograph the sun without filters by watching its image on my digital screen. • The morning air was cool and damp. Cicadas screeched from a distant stand of trees; the moist wind blew in gentle puffs swaying the grass in a rhymical dance amplified by its seed-laden sheaves. A rooster crowed. A stand of grey clouds guarded the west against a darkened landscape as the sun approached the horizon. Rising like a swollen, red orb against the grey, striated clouds, it sparkled through the branches of a distant tree. • This sunrise was much less spectacular than the August 11, 1999 eclipse when the entire sky was awash in reds and lavenders. Watching the first rays of sunlight, I realized that Sol was headed for a larger silhouetted tree and that would delay its emergence by a precious 10 minutes or so. Luckily, the grass had been matted behind me from a group of departed deer, allowing me a quick escape with my camera to a new location that was well beyond the road. Crescent Sol with its lunar drape emerged minutes after its official rise, cradled in the hollow between two trees. The atmospherics with its linear clouds reduced the brightness of the sun perfectly, allowing me to capture the event without filters while watching my external viewing screen and without imposing any danger to my eyes. • This was my second sunrise solar eclipse. I cannot emphasize how rare and precious these events are and how fortunate I have been to see two of them. It was just the start of a wonderful birthday which continued with an additional five hours of sleep when I returned home, the processing of the photos in the afternoon, ending with a sumptuous dinner and conversation with Bill and Johnny, friends who Sue and I had not seen for almost two years because of the pandemic. It was one of the best birthdays ever. My pictures of the eclipse are below.

The partial solar eclipse of June 10, 2021 was seen against the background of distant clouds making this sunrise event special and able to be photographed without any filters. Because the sun was observed from my digital viewing screen, there was no danger to the eyes. The last exposure of this series was 1/8000 second at F/40. Yes, even when seen through clouds, the sun is very bright. Images by Gary A. Becker...

1296 June 20, 2021: ’Tis the Season of Summer: Sunday, at 11:32 p.m., the sun will be shining directly over the Tropic of Cancer at local noon. For the Lehigh Valley and positions near 40 degrees north latitude, the day has lengthened to nearly 15 hours from sunrise to sunset. If the time of the first detectable light of dawn to the last glimmer of evening twilight are added to the day’s length, then we receive nearly 18 hours of light. It’s summertime “and the COVID is waning.” • Summer begins most often on June 21, but with the leap year adjustments to the calendar that we made in 2020, and particularly the once-in-every-four-century leap year correction made in 2000, summertime for the Lehigh Valley is occurring on June 20 at least once every four years. It will transpire again for Eastern Daylight Time (EDT) in 2024 and 2025. The rarest date for the summer solstice is on June 22 which will not occur until the year 2203. See the dates of summer solstice for 400 years below. • Keep in mind that the summer solstice is a moment in time that is triggered when the sun lies at the zenith over the Tropic of Cancer at high noon. This moment is reflected against the 24 time zones worldwide. As an example, although this solstice happens on the same date across the entire United States, east of the US in the Atlantic Time Zone in maritime Canada, summer begins on the 21st. Europe and Asia eastward to the International Date Line also experience the solstice occurring on the 21st of June this year. • The seasons manifest themselves because the Earth’s axis is tilted 23.5 degrees to the perpendicular to its orbital plane. When the axis leans toward the sun, the Northern Hemisphere benefits from the sun’s greater insolation (energy received); the days are longer, the sun is higher in the sky, and the sun rises and sets with a northerly component. At the summer solstice which means sun still or sun standstill, these effects are maximized so that we observe the longest day, the highest altitude of the sun at noon, and the greatest northerly rising and setting directions of the sun. The amount of solar radiation that is being received is at its greatest. • The sun is likewise “stilled” in the Southern Hemisphere, but because Sol lies over the Tropic of Cancer in the Northern Hemisphere, the day is the shortest, the sun reaches its lowest noontime altitude, and the sun rises and sets with its greatest northerly components. • Keep in mind that while all of this is taking place, the Earth reaches its greatest distance from the sun about two weeks after summer solstice, and its closest distance to the sun about two weeks after the winter solstice. The changing seasons have virtually nothing to do with our distance from the sun which changes by only 3 million miles each year. The Southern Hemisphere experiences high sun when the Earth is closest to Sol; however, the more numerous oceans in the Southern Hemisphere have an enormous capacity to absorb this extra heat, actually making the Southern Hemisphere cooler than in the north. Have a great solstice day and a wonderful summer!

1297 June 27, 2021: Spying on this Week’s Sky: We have reached that time of the year when the nights are the shortest, only about nine hours in length for 40 degrees north latitude. While the calendar says summer, the heavens are a little slower to react. The summertime constellations do not become dominant until around 1 a.m. near the time of the solstice. • The Big Dipper, high in the northwest, is starting to turn downward in its circling of the sky, a sure sign that summer is upon us. Follow the arc of its handle to the fourth brightest nighttime star, Arcturus, high overhead. If you continue along that imaginary curve, Spica will be spiked. Arcturus is the brightest star in the spring sky, a yellowish-orange giant nearing the end of its existence, while Spica is a blue supergiant, burning the candle at both ends, a sure sign that its life will be short, but noteworthy. It has a luminosity of about 5500 suns, and with a mass of 11.5 times greater than our daystar, it could very well go supernova in several million years. • Below Arcturus in the southeast, the summer star patterns are rising, Ophiuchus the Serpent Bearer and Scorpius the Scorpion. In the east is my favorite summer asterism, the Great Summer Triangle, composed of Deneb in Cygnus the Swan, Vega in Lyra the Harp, and Altair in Aquila the Eagle. Vega, the fifth brightest star of the night and just 1.85 percent fainter than Arcturus, is a normal hydrogen burning star similar to Sirius, the brightest luminary of the night, but only three times farther away. Its distance is 25 light years. Altair is about half as luminous as Vega, but at 17 light years from our solar system, Altair pulls its brightness weight in delineating the triangle’s boundaries. The weakest contributor, Deneb, is ironically the most luminous star of the group. At a distance which could be as great as 3200 light years, it may very well shine conservatively with a luminosity of 54,000 suns. If Deneb were to be placed at the distance of Vega, it would light up the night with the brightness of a thin crescent moon, able to cast shadows on the ground from a rural area and easily visible in the daytime. • What planets are currently in the sky? There is a newbie in the WNW. Brilliant Venus is low to the horizon and will stay that way throughout the summer months, disappearing in the WSW by mid-September. You’ll be able to catch it easily with the unaided eye 30 minutes after sundown, but you will probably need binoculars to see its nearby companion Mars, which will be located nine degrees above and to the left of Venus. Yes, the Red Planet, so conspicuous late last summer and throughout the fall, is still hanging around, waiting for the sun to overtake and outrun it in early October. However, rather than being in the brightness league of Jupiter as it was last year, it is now nearly 60 times fainter, about as intense as the more luminous stars of the Big Dipper. Jupiter and Saturn make their debut low in the southeast about 1 a.m. this week, but by the beginning of August, that time will have shifted backwards to 10:30 p.m. Keep looking up and enjoy the nighttime splendor!