StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

JUNE 2014

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:

928 JUNE 1, 2014: No Show Camelopardalids: It was just one of those events that you couldn’t pass up. Five orbital theoreticians had predicted that the Earth would pass through the dust strands of Comet 209P/LINEAR’s tail on the morning of May 24 between the East Coast hours of 2-4 a.m. The promise of hundreds of bright, slow moving meteors radiating from the obscure star pattern of Camelopardalis the Giraffe, located near the North Star, signified a major event. It was cloudy throughout most of PA on the 24th, so Boyertown Planetarium director, Peter K. Detterline, his son Michael, and I decided to search for clear skies along Virginia’s Skyline Drive in Shenandoah National Park. It was a five hour drive for me, but the site we found was truly spectacular, with a subdued light dome from the Capitol about 70 miles to the east and virgin skies in the direction from where the meteors would be streaming. We were in full operation by 1 a.m. Pete faced south, and I looked north in the direction of the radiant. For nearly four hours we watched intently and saw almost nothing, in total, four faint Camelopardalids (Cams) and nine nonmembers for me. Ironically, I imaged a Cam which I don’t remember observing. Pete fared better with five faint Cams seen and seven sporadic meteors spotted. Perhaps Michael was the luckiest. He fell asleep almost as soon as we started viewing. The brilliant fireballs predicted by the experts did not materialize, and as the blue dawn invaded the darkness with Venus and a thin crescent moon hanging over DC, we contemplated another five hour journey home. I went a total of 27 hours without sleep, but there was definitely a sense of satisfaction about being a participant in the verification of this event. In meteor astronomy, these types of forecasts are still in their infancy. The lack of confirmation of a meteor show was every bit as valid from a scientific standpoint, but it is back to the drawing boards for the theoreticians.

929 JUNE 8, 2014: Clear Skies Guaranteed for Saturn Conjunction: It has never rained on my birthday. That fact was told to me by my mother about 20 years ago, and since then, I have observed that she has been correct. That doesn’t mean that conditions on every birthday have been sunny and mild, but wherever I have been, it has never rained—not a drop. So against very good odds, I’m predicting that you will see a relatively close conjunction of the nearly full moon and the planet Saturn on Tuesday, June 10. Of course, you’ll have to be where I’m located, and that datum has yet to be revealed. Actually, the concept of a conjunction is fairly simple. It is the alignment of two solar system objects when positioned at the same celestial longitude. In a terrestrial analogy, that would be like saying Philadelphia and Easton, PA are in conjunction because they are both positioned at 75 degrees west longitude or 75 degrees west of Greenwich, England. However, Philadelphia and Easton will always be in conjunction because they do not move relative to the Earth’s surface. The solar system is dynamic, meaning that conjunctions come and go and repeat themselves in predicable patterns. Also, since the sun, moon, and planets are essentially in the same plane called the ecliptic, a conjunction means that the participants will always be in close proximity to one another; but the term really has a much broader implication and is associated with the concept of two celestial objects simply being near each other. So a planet and a star, other than the sun, located near the ecliptic, such as Regulus, Spica, Antares, Aldebaran, and others can be said to be in conjunction with the planets, sun, moon, and even asteroids. On Tuesday evening, use binoculars to enhance Saturn and the moon, even though they will be visible to the unaided eye and remember; the weather is guaranteed to be at least rainless, but hopefully perfect, because this conjunction will occur on my birthday.

930 JUNE 15, 2014: Summer Solstice or a Midsummer Night's Dream: It is the week of the summer solstice. Steadily since December 21, 2013, the sun has climbed higher into the sky, slowly at first, fastest at the spring equinox, and now leisurely again as it ekes its way to the top of its arc above the celestial equator. High sun will be reached on Saturday, June 21, at 6:51 a.m. EDT. The word “solstice” means “sun still” or “sun standstill,” a time when the sun pauses in its change of altitude, and therefore, does not alter its rise or set positions along the horizon. During the week before and after the solstices, the sun will change its noontime elevation by less than one quarter degree, indeed virtually standing still in its upward and downward motions. Even a month before and after the solstices, Sol’s altitude change is slightly less than three degrees or about six solar diameters as viewed in the sky. However, there is a second way to interpret the times of high and low sun, and that is by calling the days when they occur midsummer and midwinter which is the way they are often denoted in Great Britain. Since the vernal equinox, when the sun pushed north of the equator (March 20), Sol has continued to climb ever higher into the sky. It reaches its most elevated position on June 21, then begins a slow descent until it crosses the equator again on the autumnal equinox (September 23). At the midpoint between these equinoxes, the sun reaches its highest altitude at its “midsummer” or solstice location. I first encountered this term when I began to take an interest in understanding megalithic sites in Great Britain, such as Stonehenge. I think that most Americans instinctively would consider midsummer to be understood as the middle of the summer or about August 1 when temperatures are peaking, but in reality it applies to the solstice. High summer or the “dog days of summer” are the terms used for the hottest, sultriest time of the year. So will it be the summer solstice or midsummer? It’s your decision because they are both correct.

931 JUNE 22, 2014: Meteorites Tell Stories of Times Past: I’ve been scouting for meteorites on eBay for the past week. It has become somewhat of an annual tradition which has resulted in the discovery of dealers who are knowledgeable, provide accurate descriptors, and document their space rocks with good photographs. Many retailers are members of the International Meteorite Collectors Association (IMCA), a group of buyers and sellers that police the market looking for dodgy dealers and meteorwrongs, fakes that are really terrestrial in origin or human made. Many meteorites are rather dull and unattractive. In fact, I have often joked that the most unappealing displays at large mineral and fossil shows are the meteorite dealers. So what is so appealing about owning a few rocks from space or for that matter collecting them? One factor is that a meteorite has spent virtually all of its existence in space. The meteorites that fall to Earth today were broken up only 50-500 million years ago in collisions among larger bodies, signifying that new supplies of space debris continue to be generated for the Earth and other planets to encounter. Hold a meteorite in your hand, and you are witnessing something as old as the solar system itself, 4.5+ billion years. The breakups may have been recent history, but the bodies from which they originated, formed about the same time that the Earth was accreting. One of my favorite meteorites is a tiny one gram slice of the Monroe which fell to Earth at 3 p.m. on October 31, 1849 in the future confederate state of North Carolina. It is chock-full of small spherical bodies called chondrules. See the online picture. These were the first dust packets of accreting matter in our planetary system. They were heated, melted, and frozen into spheres which stuck together in ever increasing numbers as the sun’s nuclear furnace ignited. What a wonderful treasure it is to possess as visual proof a small “piece” of the solar system’s birth.

932 JUNE 29, 2014: Earth at its Greatest Distance from Sun: One of the astronomical misconceptions which I always try to correct with my students is that the seasons are a function of the Earth-sun distance. It does make sense to think that being closer to the sun should result in warmer conditions. After all, we have had so many similar experiences with campfires, hot stoves, and clothing irons, that it seems perfectly logical to assume that our seasons must somehow relate to distance. They don’t. In fact, on July 3 at 8:00 p.m., EDT, Earth will have receded to its farthest distance from Sol, 94,519,300 miles. What gives? If the Earth’s axis, the imaginary line about which the Earth rotates, was perpendicular to its orbital plane, we would have minute changes in temperature because of distance, and this would be the ever so slightly cooler time of the year. However, the Earth’s axis is inclined, and that tilt, 23.5 degrees from the perpendicular to its orbital plane, creates the effects which give rise to the seasons. Although the Earth is at its greatest distance from the sun in early summer, the northern hemisphere tilts towards the sun causing Sol to be higher in the sky and to shine upon us more directly. The sun is also visible for a much longer duration of the day. This results in a greater amount of energy being absorbed by the northern hemisphere, and higher temperatures are one of the results. The concept of direct and indirect energy can be aptly demonstrated with a flashlight. If you want to illuminate something fully, you shine the light directly on it. The beam of light is narrower, but the object is lit more intensely. Likewise, when you are looking for that small screw which just dropped onto your dark linoleum floor, you hold the flashlight horizontally to its surface, spreading the beam as widely as possible to catch the direct glint of the screw or possibly its shadow stretching across the floor. Summer is the time of the direct sun and longer days, even though Earth is farthest from the sun.

[June Star Map]

[June Moon Phase Calendar]