StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

JUNE 2018

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:

1137 JUNE 3, 2018: June Skies, Hopefully Clearer: Let us hope—pray—beg that June is not as cloudy as May. Even some of the good nights last month turned out to be dew-laden, not a fun experience if you’ve got your scope out, and it gets fogged or starts dripping from the condensation of water. As June begins, Venus is still the dominant object of the dusk sky, wonderfully bright and relatively high in the west. It shares the twilight heavens with a thin waxing crescent moon on the 15th and 16th and with a rapidly changing Mercury by the end of the month into the first week of July. The other planet to keep tabs on is Jupiter, continuing to be better and better placed in the evening sky. At dark in early June, Jove is playing its reflectance just to the east of south, but that changes to the west of south by month’s end. It will be the prominent object in the evening southern sky throughout June. As July approaches, however, there is another newcomer in the southeast, Saturn. Nearby trees may still hide it as the skies darken, but by midnight it should be plainly visible in the south. If you’re wondering what that unusually bright object is next to the moon around midnight on June 30, try reddened Mars which will reign supreme during the late summer. Currently, high in the north by 10 p.m., the Big Dipper is just starting to make its downward turn, with the bowl lower than its handle, a sure sign of the warmer days of summer to follow. The star, Polaris, around which the northern heavens pivot, can be easily found. Follow the Pointer Stars (lowest) of the Dipper’s cup, Dubhe and Merak, to the right and down in a straight line to find it. The Pole Star’s reputation results not from its brightness, but rather from its stationary position, marking the direction north and the location in the sky to which the Earth’s rotating axis points. You can demonstrate this concept by simply looking straight up into the sky and finding the nearest star overhead. Rotate (spin) slowly and watch as all of the heavens seem to circle around the axis of your body and create your own personal “North Star.” Rotation is just one of many different motions that affect the positions of objects in the sky with respect to the horizons and zenith or in regards to each other. Revolution, precession, nutation, the aberration of starlight, parallax, astronomical refraction, and proper motion come to mind. Thank goodness for computers. Above Polaris and about as high in the sky as they can climb are the second and third brightest stars of the Little Dipper (Little Bear—Ursa Minor), Kochab (left), just a smidgeon dimmer than the North Star, and Pherkad, about two and one-half times fainter. These stars mark the top of the bowl of the Little Dipper, which can only be seen in its completeness from rural locations. However, binoculars will allow you to see the entire star pattern even from an urban locale. Bisecting a line between Kochab and Pherkad to Mizar, the middle star of the Big Dipper’s handle will bring you to a pair of stars in the tail of Draco the Dragon. The brighter member is Thuban, the north star of Ancient Egypt’s Old Kingdom. The Earth’s axis wobbles (precesses) approximately once every 25,772 years like a giant top in a 47-degree circle. Currently, the axis points towards Polaris, but by 14,000 AD, Vega in Lyra the Harp, that bright star nearly mid-sky in the early evening east, will be our pole star. Allow your eyes to sweep in an arc from Vega to Polaris to Thuban and you will trace the circle around which the axis pivots in nearly 26,000 years.

1138 JUNE 10, 2018: Crescent Moon Woos Venus Late This Week: The moon is new on June 13 which means that coupled with transparent skies, your opportunities for viewing celestial objects are enhanced. Friday and Saturday, June 15-16 offers the best opportunities for seeing the second brightest sky object, the moon, next to the third brightest object, Venus. The pairing will not be especially close, about 7-1/2 degrees for both evenings by the time of darkness on the East Coast, but it still will be an inspiring sight to behold in the western sky. The moon will be below and to Venus’ right on Friday and above and to the left of the Goddess of Love on Saturday. Look for earthshine on the unlit portion of the seven percent waxing crescent moon on Friday and also on Saturday when Luna has grown to nearly 15 percent illumination. To me these types of events are the most stunning when there is some residual twilight in the sky. I don’t think you’ll be disappointed if you view about 30-40 minutes after sundown. Bring binoculars along to enhance the earthshine, light reflected from a nearly full (fat gibbous) Earth rebounded back to us from the unlit portions of the moon. Also, on the 16th with binoculars, you can scan between the moon and Venus and spot a faint grouping of luminaries. That’s the Beehive star cluster, also known as the Praesepe (Latin for manger), and designated as M44, the 44th object cataloged by Charles Messier (1730-1817), a French astronomer who was more interested in discovering comets than viewing celestial showpieces. When Messier came across fuzzy, stationary objects during his sky sweeps that his small telescopes could not properly resolve, he noted them to avoid the embarrassment of announcing the false discovery of a comet. Many of his findings, such as the Beehive, were either known in antiquity or first discerned by other sky watchers but then chronicled by Messier, perhaps to boost his catalog numbers. The current listing contains 110 objects, 103 which were published in his last catalog in 1781. What makes Messier fascinating is that he did make 13 original comet discoveries. Most of them never became very bright, although his sighting of August 8, 1769 became easily visible to the unaided eye and has been classified as a great comet while his comet discovery of 1770 came within 1.4 million miles of Earth. Still, Messier is remembered for what he was trying to avoid, some of the most spectacular star and globular clusters, nebulae, and galaxies of the northern hemisphere, rather than the comets which he first witnessed. The Beehive is one of the easier Messier objects to view, although I never saw it as a swarm of hovering bees. Under a dark, moonless early spring sky, when it is much higher in the heavens, it can be observed with the unaided eye as a faint, nebulous looking object, but it is really composed of just over 1000 stars. M44 is relatively close, about 600 light years distant and about 600 million years of age, which is relatively old for a star cluster. Most open clusters evaporate as outer members stray, and the cluster loses mass. To the left of the moon on Saturday will be Regulus, the “king” of the stars of Leo the Lion. Look for the sickle, the head appearing as a backwards question mark, diving towards the western horizon as the spring stars set earlier and earlier each evening, and the summer stars begin to take center stage in the east.

1139 JUNE 17, 2018: Winter Already Visible in Summer’s Sky: Summer is finally here. If you are one of those individuals who has to know the exact moment when the sun has reached its greatest deviation north of the equator, it is on Thursday, June 21 at 6:07 a.m., EDT according to the Observer’s Handbook. My computer program says 6:09 a.m., so perhaps we should split the difference and say 6:08 a.m. I’ll be in my comfy bed fast asleep when it happens. After the 21st it’s all downhill for ole Sol as he slowly begins his descent which will culminate in our lowest sun happening on December 21 at 5:23 p.m. That’s six months from now, but the heavens are already making its case. The summer constellations are now debuting in the eastern sky as the spring patterns begin to move farther west of the meridian on each successive evening. Around 10 p.m. when the sky has darkened sufficiently, look for three stars in the east forming the asterism of the Great Summer Triangle. It’s big and easily seen. Asterisms are like constellations, but not officially recognized by the International Astronomical Union, the clearing house for what’s official in the sky. The top star is the brightest, Vega, about 25 light years distant, followed by Deneb on the left. According to the European Space Agency’s Hipparcos catalogue, Deneb is about 3000 light years away, making it the brightest star for its remoteness visible in the entire sky. Ironically, Deneb is the faintest luminary of the three because of that remoteness. Altair is to the right, 17 light years away. If compared with each other at a standard distance, all three stars would be brighter than the sun, but it would be Deneb that would turn us into toast the fastest if moved to the sun’s distance from Earth. Looking south at 10 p.m., Tuesday or Wednesday, the nearly first quarter moon, Jupiter, and Saturn will be strung out like a set of uneven pearls in the south. Far to your right in the northwest will be brilliant Venus. If you connect Venus, the moon, Jupiter, and Saturn, you’ll obtain a very close approximation of the ecliptic, the path of the sun among the stars, created by the Earth’s revolution (orbiting) around Sol. You’ll notice at once that the moon, Jupiter, and Saturn are all very low in the south. This is where the sun will be placed in September (moon’s location), November (Jupiter’s position), and December (Saturn’s vicinity). You are viewing a precursor to future seasonal changes when the sun will be at its nadir in the daytime heavens, visible for only nine hours, and rising and setting with a far southern component. The “why” behind all of these changes arises from the fact that Earth’s axis is tilted to its orbital plane, causing the sun to be high and mighty during the summer while low and weak during the wintertime. It’s still the same sun—we are actually closer to it in the winter—but the low sun angles of winter cause its energy to be spread over a greater area, thus becoming less effective in warming the mid-latitudes of the northern hemisphere. The shorter time the sun is visible during the daytime is also a major factor in the plummeting of temperatures. There is one last star I’d like you to notice. Between Jupiter and Saturn is the alpha star of Scorpius the Scorpion. It goes by the name of Antares, Greek for “the rival of Ares,” the god of war, Mars to the Romans. Later this summer, ruddy Mars and reddish Antares will take center stage in the southern sky and because of its reddish color, it will be easy to understand why Antares received its name. Keep looking up. The heavens always hold something interesting to observe.

1140 JUNE 24, 2018: Rocket Girls Soars: When Nathalia Holt’s Rise of the Rocket Girls: The Women Who Propelled Us, from Missiles to the Moon to Mars (Back Bay Books, 2016) was gifted to me by my wife last Christmas, I immediately thought of Hidden Figures. Was this the white rebuttal to the racial injustices heaped upon women of color who worked as computers at Virginia’s Langley Research Center? Refreshingly, it was not, but rather the evolution of the women who served as the human computers and eventually the programmers of Caltech’s Jet Propulsion Laboratory which was first taken over by the Army and finally amalgamated into NASA’s family of research facilities in December of 1958. It all began in 1936 with several rocketry experiments conducted near the Caltech campus. The three men involved, only one who was a Caltech student, became known as the Suicide Squad. On campus (1939) they failed miserably in several dangerous experiments damaging the Guggenheim Aeronautical Laboratory and were forced off campus. Still the fledgling group received grant money from the National Academy of Sciences, settling in the Arroyo Seco where they had performed their original experiments, away from people, but still near to Caltech. It is today’s JPL campus. It was here that 19-year old Barby Canright became the first computer. Computers from the 1700s up until the utilization of more modern machines were comprised of men and women who crunched the numbers manually to certify that the parameters of the experiment were being met successfully. By the twentieth century in the United States virtually all of the human computers were women who had high aptitudes for mathematics. At JPL, some were hired right after graduating from high school. These same women and new recruits also evolved into the first computer programmers as technology evolved in the decades of the Space Race and beyond. Under Army auspices, JPL competed and lost in the race to develop the ballistic missiles that drove the Cold War. However, in the peaceful pursuit of space, they scored the first major victory for the US with the launching of Explorer I on January 30, 1958. The mathematics which governed the trajectory and successful deployment of the instrument package of Explorer I were performed by the female computers of JPL. When the Jet Propulsion Laboratory became part of NASA, JPL was put in charge of developing the rocketry and technology that successfully explored the solar system, and its female computers were an integral and cherished part of JPL’s success story. Unlike Hidden Figures where maintenance of the status quo and a greater deal of formality were always in evidence, the computers at JPL were an openly admired part of the work force. Computers mixed with other professionals in the lunchroom and at JPL parties, dated and married engineers, became engineers and supervisors in their own right, raised families, left and returned to work in much more of an open environment than seemed present at Langley (Hidden Figures). Friendships, however, away from the workplace were present in abundance at both centers. Divorces were also a part of the JPL scene, where careers sometimes took precedence over homelife, a prelude to the “modern family,” and the emancipation of the American woman. I would recommend Rocket Girls, as well as again, Hidden Figures (StarWatch 1082, May 14, 2017), to understand more faithfully the vital role which women played in America’s race to space.

[June Star Map]

[June Moon Phase Calendar]