StarWatch for the greater Lehigh Valley
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NOVEMBER  2019

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

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1211    NOVEMBER 3, 2019:   Mercury to Transit the Sun, November 11
It only happens 14 times this century in either May or November. You will have to look at the filtered sun to see it, and you will need a telescope to boot. On November 11, starting just after 7:36 a.m. EST and continuing until just after 1:04 p.m., the Messenger God, Mercury, will be swiftly crossing—transiting, the disk of our sun. Transits are similar to eclipses which hide the sun or the moon, but in a transit the occulting object is much smaller; in this case, the planet Mercury, is only 10 seconds of arc in diameter. That is equivalent to viewing a 12-mile in diameter crater on the moon’s surface. However because the filtered sun is still bright, and Mercury is black against Sol’s disk, the silhouette of Mercury will show up easily. Transits of Mercury and especially Venus are rare because the alignment of Earth, planet, and sun must be virtually dead on. Mercury orbits Sol in a period of only 87.97 days, while it takes the Earth 365.24 days to complete the same (tropical year). Mercury’s orbital tilt is 7.01 degrees to the plane of Earth’s orbit called the ecliptic. This means that as Mercury revolves around the sun, it must cross the ecliptic at two locations (nodes), a descending node, where it moves from above to below the ecliptic, as well as an ascending node where Mercury crosses from below to above the ecliptic. For a transit to occur, Mercury must be at a node just as it is moving exactly between the Earth and the sun. That puts a high price on the frequency of Mercury transits and relegates them to a position of rarity among astronomical events; something you don’t see every day or don’t want to miss. Transits of Venus are even rarer, occurring in eight-year intervals separated by interludes of 105 years or 122 years respectively. We’ll have to wait until December 8, 2125 before the US sees its next Venus transit. I was fortunate to witness the Venus transits of 2004 and 2012, the maximum number of transits possible to view in a single lifetime. If successful, this will only be the fourth transit of Mercury that I have witnessed even though 11 have occurred since my birth. Three Mercury transits happened prior to age 11 before I knew what a transit was, some were not visible in our part of the world, and others were ruined by cloudy weather. That could easily happen in November, one of the cloudier months of the year. Locally the long-range forecast for the Lehigh Valley on transit day is for cloudy skies, but that is still a week off, and when preparing for any rare sky event, you strive to remain optimistic and plan for success. Hang in there; more about the Mercury transit next week.
 

1212    NOVEMBER 10, 2019:   Transit: “Weather” or Not?
If you reside east of the Mississippi, it seems as if virtually all astronomical events live under an umbrella of unreliable weather. During my lifetime the scores of major astronomical events that I have witnessed, only one, the annular (solar) eclipse of May 20, 2012 was seen under a totally clear sky. That event turned out to be near Nageezi, New Mexico. Too cold, too cloudy, too windy, too something, always seems to put a damper and additional angst on the expectancy of a successful view. That is the doom and gloom that I felt as I began writing this article on November 7 regarding the transit of Mercury which will be occurring on the morning of November 11 from 7:36 a.m. to 1:04 p.m. Transits of planets across the sun’s disk are very rare. I’ve seen two transits of Venus, the most that anyone can witness in a lifetime, and also three transits of Mercury. All had weather issues. The 11th of November could be my fourth with cooperative skies, but if it is cloudy and I miss it, my next opportunity to see Mercury against the face of the sun will be happening on November 13, 2032, followed by another transit on November 7, 2039, both best seen from the eastern hemisphere. The next good East Coast transit is May 7, 2049. I was born in June of 1950. You do the arithmetic! I’ve spent hours looking at data from the National Weather Service, but the best predictor of these types of events is my good friend and former pupil, Adam Jones, who graduated with a degree in meteorology from Penn State University and now lives in Denver. As a PSU student, Adam beat his professors and the college’s computers in making accurate and precise forecasts. On November 8, Jones felt that Assateague Island, Maryland had the best chance of viewing the Mercury transit with, a sea breeze aiding in keeping the clouds at bay for a longer duration of time. Locally, he predicted mostly cloudy to cloudy conditions during the transit and indicated that we might not witness anything at all. We’ll see how things materialize. The Lehigh Valley Amateur Astronomical Society will be viewing the Mercury transit on November 11 from the east side of the Da Vinci Science Center at 3145 Hamilton Blvd Bypass, Allentown, PA 18103/484-664-1002 from about 7:30 a.m. to the end of the transit just after 1 p.m. Because of the mostly cloudy weather forecast, I would suggest phoning the Da Vinci Science Center to make sure the event has not been cancelled. Other more remote readers of this column might want to contact the Astronomical League at https://www.astroleague.org/ and click on astronomy clubs. Find the one closest to you and use the League’s contact form to see if club members will be sponsoring a transit watch that is open to the public. Much success to all in obtaining a glimpse of this very rare event and special thanks to Adam Jones for his insights.
 

1213    NOVEMBER 17, 2019:   Mercury Transit—A Success!
Whether or not the November 11 transit of Mercury across the sun’s disk would occur was never an issue. These types of events are predictable thousands of years into the future. Whether we’d see it or not because of bad sky conditions was up for grabs. South on Assateague Island, Maryland, where friends, Peter Detterline, Dean Bauer, and I traveled to view the event, success ruled the day, even though most of the transit was viewed through high clouds. The event sponsored by the Lehigh Valley Amateur Astronomical Society at the Da Vinci Science Center in Allentown also went off without a hitch. I actually didn’t commit to Assateague until about noon on Sunday, just hours before Dean and Pete left for Maryland, but admittedly, I hedged my bets by getting my gear together the previous day. When I saw a 68 percent cloud cover for the transit times in the Valley and only 7 percent at Assateague, I decided to make the leap. Our five-hour trip including dinner got us to our campsite after dark under clear skies with the light from a fat, waxing gibbous moon aiding our efforts to set up in the dark. Happily, everything went smoothly. Dean handled all of the camping chores while Pete and I assembled our scopes and performed initial testing which included a precise alignment on the North Celestial Pole, the pivot point around which the Earth rotates and absolutely necessary for allowing the telescope drive motors to follow the stars, sun, and moon accurately. By 10:15 p.m., I was tucking myself into my down mummy bag that quickly made me warm and content. The rhymical ocean waves crashing upon the shores of Assateague Island capped by a moon-drenched landscape soon lulled me into a deep sleep which lasted until just after 4 a.m. It was a magical experience and an almost unique one for me because I rarely sleep at all before a big astronomical show. This time, however, I awoke refreshed and ready to witness the last transit I would see in my lifetime from the East Coast. Emerging from my comfy bag around 5 a.m. with a crimson glow in the east, I quickly discovered one of Assateague’s famous wild horses munching some grass a few dozen yards from my tent. The sunrise was spectacular complemented by a young couple snuggling for warmth on an empty beach as the cold orb of the sun broke the horizon in the east. It was time to get ready, time to take the scopes from hibernation, time to slew them towards the sun, and time to check on those first exposures to square things away and to ensure that all was ready for the big event. On cue at 7:35 a.m. Mercury entered the sun’s domain; Earth, sun, and Mercury aligned so precisely that the Messenger God crossed (transited) the sun’s disk during the next five-and-a-half hours. It was exciting, a rock concert for observational astronomers, and slowly “inch by inch” Mercury crawled across the face of Sol with every park ranger and park volunteer visiting, and dozens of people showing up from other parts of Assateague to drop in and share our scopes for a look and a long chat. It’s amazing how the word got out. It was also amazing to see Mercury in the daytime crossing the face of Sol. Thanks be to a sun that shone brightly enough on Veterans Day so that we all could witness this extremely rare astronomical event. Photos are online at https://astronomy.org/StarWatch/November/index-11-19.html#11-17-19.

[Mercury Transit]
Peter K. Detterline horsing around before sunrise on Assateague Island National Seashore... Photography by Gary A. Becker...

[Mercury Transit]
I believe that sunrises are highly overrated, but not this one. Photography by Gary A. Becker...

[Mercury Transit]
Dean Bauer was a student of Peter Detterline during Pete's first year of teaching in the Boyertown (PA) Area School District. In the same fashion, Pete was my student teacher during the spring of 1981. The breakfast that Dean served to us on transit morning was one of the best that I have ever tasted. Photography by Gary A. Becker...

[Mercury Transit]
Pete Detterline (l) and Gary A. Becker have traveled tens of thousands of miles chasing eclipses, comets, transits, and volunteering at the Mars Desert Research Station near Hanksville, Utah. In 2020, it’s off to South America and Antarctica with friends including Dean Bauer. Photography by Gary A. Becker (l) and Peter K. Detterline...

[Mercury Transit]
The transit of Mercury across the sun's disk happened on November 11, 2019. Photography by Gary A. Becker using a 3.5-inch Questar...

[Mercury Transit]
The transit of Mercury recorded in hydrogen alpha (l) and in white light... Photography by Peter K. Detterline...
 

1214    NOVEMBER 24, 2019:   Venus Grouping on Tap this Week
Finally after months of waiting, Venus is becoming more easily visible in the west after sundown. Observers with nearly perfect sunset horizons began seeing Venus in bright twilight in early October, but its setting time remained nearly constant with regard to sundown. This is because during early fall the sun’s and Venus’s paths against the sky were tilted at such a low angle to the horizon that Venus struggled to gain any altitude as it moved away from Sol. The situation is analogous, but in reverse to Luna which rises in the east nearly at the same time when close to its full phase during the early fall months. The shallow angle of the moon’s orbital path to the horizon creates the effect of the Harvest Moon, the name of the full moon closest to the autumnal equinox which rises nearly at the same time over the course of about five days. Venus orbits the sun in nearly the same plane that Sol moves, the plane of the ecliptic, but it has now traveled away from the sun far enough so that its visibility has improved and will continue to get better as we head into the New Year. By mid-January 2020, the ecliptic will have already started its spring like appearance, tilting at an ever-steeper angle to the horizon. Venus will continue to pull away from the sun, rising rapidly in altitude in the dusk sky to become the evening’s most prominent member other than the moon. By March 24, the ecliptic will be virtually at its greatest tilt to the horizon; Venus will be farthest from the sun, at its angle of greatest (eastern) elongation, 46 degrees above the skyline at sundown, about as good as it gets. Venus will set at 11:20 p.m., a dazzling white diamond in the early spring sky. By income tax day, April 15, Venus’s setting time will be increased by an additional 20 minutes; then the Goddess of Beauty rapidly begins to decrease its angular separation from the sun, missing Mercury by just over a degree on May 21/22 and gliding past the sun’s limb on June 3, 2020 when the Messenger God is at inferior conjunction. This week, Venus is still low, about 10 degrees above the WSW horizon, 30 minutes after sundown. With clear skies and a southwestern skyline that is uncluttered with buildings and trees, this celestial beacon should be easy to spot, but if you have binoculars, bring them along because there is much more to see. Venus will also be very near to Jupiter on Sunday and Monday, with Venus’s distance left of Jove widening throughout the week, but still within the same field of view using average binoculars. Above and to the left of Venus by about 15 degrees will be Saturn which will become much easier to spot as the sky darkens. The moon even gets into the act, as an ultra-thin, 6 percent waxing crescent on Thanksgiving evening just above Venus and as a thin 12 percent lit crescent just below Saturn on Friday. View about 45 minutes after sundown to catch earthshine from the moon, light from a nearly full Earth reflecting back to us from Luna. The portion of the moon not being lit by sunlight should have a ghostly appearance, very spectacular when seen through binoculars. Good naked eye and binocular observing awaits this week if the weather cooperates. Go to https://astronomy.org/StarWatch/November/index-11-19.html#11-24-19 for a map of the week’s activities. Much success!

[Venus Grouping]
Graphics by Gary A. Becker using Software Bisque, The Sky...
 

[November Star Map]

[November Moon Phase Calendar]
 

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