StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

SEPTEMBER 2014

SEPTEMBER 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:

942 SEPTEMBER 7, 2014: Harvest Moon Shine Down on Me: On Monday, September 8 at 9:38 p.m. EDT, the Harvest Moon occurs. It is the full moon closest to, or nearest after, the autumnal equinox. The equinox happens on Monday, September 22 at 10:29 p.m. EDT; so it is a “nearest situation” for this year, with the Harvest Moon taking place 14 days prior to the equinox and the next full moon happening early on the 8th of October, 15 days past the equinox. The Harvest Moon has a definite relationship to farming. In our mechanized world where harvesting crops after sundown can be as easy as turning a switch to engage the lights, it is sometimes difficult to comprehend why this moon was so important centuries ago. Any moon near its full phase is extremely bright, and you can prove this for yourself by simply going outside and standing under its light. Let your eyes adjust to the darkness for several minutes, and stay away from any streetlamps. You’ll witness an astonishing amount of detail becoming visible all around you. My grandfather, Ewald Marcus, who was a cook in the German army fighting on the Russian front in World War I, told me stories of how he used to read newspapers by just the light of the bright moon during cold, snowscaped evenings. What makes the Harvest Moon even more special is that the tilt of Luna’s orbit with respect to the horizon is at its smallest angle during the beginning of fall. The moon trudges along at its regular orbital pace of 13 degrees per day, but that motion changes its altitude to the horizon by only a small amount. For several days around full moon, Luna rises within 25-35 minutes of its rising time the previous day. In Europe, the successive rising times are even closer together, as little as 10 minutes apart. It is easy to see how a farmer harvesting crops after sundown could have continued working late into the night as daylight transitioned into the helpful light of a bright moon, while he guided his horses along the rows of moist, furrowed ground.

943 SEPTEMBER 14, 2014: WARNING: Earth Approaching Sun: If you are a creature of habit like me, going to and from work or school at the same time, then it has been impossible for you not to have noticed the changing times and positions of sunrise and sunset and the lowering of the sun’s altitude in the sky. That westward stretch of highway where the sun was to the right (north) during the summer is now presenting you with a sun that is setting directly in front of you. But don’t worry; as the weeks pass the sun will rapidly, then more gradually, move to the left (south) of the roadway as Sol moves from above to below the celestial equator. The moment this happens is called the autumnal equinox, and this year it occurs at 10:29 p.m. on September 22. The sun is directly over the equator and now slips into the Southern Hemisphere, leaving mid-latitude and high latitude locations clutched in their seasons of long shadows and darkness. For me it inaugurates my least beloved time of the year, and my wife’s favorite. Opposites really do attract. The whole process of the seasons is a function of the Earth’s tilted axis to the perpendicular of its orbital plane. It’s not much, just 23.5 degrees, but it creates all of the effects that plunge us into the depths of winter, including the possibility of winter storms and unexpected snow days. During winter, the sun rises to the south of east by a substantial amount and sets to the south of west by the same amount because the location of the sun is well below the equator, 23.5 degrees south by the winter solstice. This more southerly exposure shortens the time that the sun is visible in the sky from rising to setting, and its lower altitude spreads out its energy across the landscape, making Sol a much less effective warmer of the Earth. All of these winter effects happen as the Earth’s orbit takes us to our closest approach to the sun in early January. Yeah, the seasons have nothing to do with the distance of the Earth from the sun.

944 SEPTEMBER 21, 2014: Merc the Jerk!: When I first got into public education in the 1970’s, I used an orrery, a mechanical model of the solar system, to demonstrate to third graders Keplerian motion. Simply put, an object located closer to a gravitational source, like the sun, orbits at a faster speed than another body which is farther away. This orrery was special because it only contained Mercury, the Earth, and the moon. So to fool the kids into thinking that Earth had to be special from an orbital sense because we lived on it, I had a race between Mercury, which I called Merc, the Jerk, and the wonderful, and beautiful “vivacious” Earth. Of course, the kids always fell for the set up and voted that Earth would win, and then were amazed to see that as an orbiting planet, Earth was nothing special. In fact, Mercury orbits the sun in only 88 days. The kids loved it, but the science coordinator for the Allentown School District thought that my language was “over the top” for a public school setting. I hung my head in shame (wink) while he lectured me on the appropriateness of words in the English language, and then went right back to using what I knew was a “kick-ass” method of getting this concept across. Merc the Jerk, for real, is visible this week if you locate yourself on beautiful, vivacious Earth where you have a kick-ass western horizon. There will be better evening apparitions of Mercury during mid-January and early May of 2015, but this week is the best and the last time in 2014 to catch the most elusive of the classical planets after sundown. Early in the week, about 20 minutes after sunset, look with binoculars very low in the WSW. A flawless horizon and a very clear evening will be needed to spot Mercury; but if you fail, note that as it gets darker, Mars and Saturn will be waiting to be revealed low in the SW. By next Sunday Mercury is gone, but a beautiful crescent moon lies between the God of War and the God of the Harvest. Good viewing!

945 SEPTEMBER 28, 2014: An Amazing Ride: Lynn Sherr’s, Sally Ride: American’s First Woman in Space (Simon & Schuster, 2014) details the incredibly complicated life of a pioneer who was quietly determined to break down barriers and succeed in an arena where only men had gone before. She was an ace tennis player when the sport was not quite ready to accept women openly as professionals; and she excelled in science and math at a time when females were cautioned that girls just didn’t pursue that career path, and wouldn’t it be better to major in English and just get married? Sally said, “No!” Then she double majored in physics and English (1973), completing her PhD in astrophysics (1978), all from Stanford. That same year she and five other women began chipping away at NASA’s all male astronaut fraternity. The successes that Sherr meticulously details were also punctuated by a more somber side about Sally’s life that virtually no one saw. She was an introvert having to play the part of an extravert when she was in public, and more importantly, she was gay, at a time when coming out would have spelled disaster to all of the career goals that had motivated her life. She was a consummate perfectionist, a workaholic, who needed to safeguard her own self-assurance by being at least as good as or better than the men and women who were competing around her. She had both male and female lovers. She married astronaut Steve Hawley (1982) before going to space in 1983, and then afterwards, began a growing emotional attachment with her eventual life partner, Tam O’Shaughnessy. This duality about her was confusing, yet everyone in her inner circle had nothing but praise and admiration for her life, her aspirations, and her accomplishments. She had no enemies and apparently no regrets. When pancreatic cancer stole her life at age 61 in July of 2012, she was doing what she loved best, helping girls and young women break barriers and reach for the stars. Ride, Sally Ride!

[September Star Map]

[September Moon Phase Calendar]