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Summer constellations

April 19, 2011
By Aileen O’Donoghue (aodonoghue@stlawu.edu) , Adirondack Daily Enterprise

As night retreats before the northward march of the sun, the winter stars fade over the western horizon. So, too, this column will fade into the bright evening.

But the summer skies offer their own beauty, so today's diagram shows the constellations at 10:30 p.m. on July 26, the halfway point to the return of The Wilderness Above next November. If you don't want to wait for July to enjoy this part of the sky, it's visible now at 5 a.m.!

By late July, Virgo, with Saturn moving away from Porrima, will set soon after darkness falls. The Great Bear has arced across the sky and, as the summer ripens into August, starts to descend to the northwestern horizon, where she will lumber into autumn. Following the arc of the bear's tail leads to bright Arcturus (arc-TOU-rus), the "guardian of the bear." One of the few stars with a name based in Greek, its root is arktos, meaning "bear," from which we get the name "Arctic" as well as Arcturus. Its orange-ish glow indicates it is an older star that has used up the hydrogen fuel in its core and is now fusing helium into carbon to produce its light and heat. That light was actually used in 1933 to open the "Century of Progress" World's Fair in Chicago. The photocell, a device that converts light to electricity, was a new technology to be highlighted. Since Arcturus was then thought to be 40 light-years away and there had been a World's Fair in Chicago in 1893, they decided to turn on the lights of the fair by focusing the world's largest refracting telescope at Yerkes Observatory on Arcturus so that its light could flip the switch by use of a photocell. They did this so the light that had left Arcturus 40 years earlier would illuminate the new fair. This was done to great hoopla! However, according to Jack Horkheimer, it was actually cloudy at Yerkes Observatory, so the switch was quietly flipped by hand! Also, the distance to Arcturus was later, more accurately measured to be 37 light-years. But no one at Chicago's party knew these things, so the celebration went on as planned.

Looking up and eastward from Arcturus, the bright white star Vega (VEE-guh) is just east of the zenith. Though slightly dimmer than Arcturus, Vega is much whiter due to the fact that it is much younger and still vigorously converting hydrogen to helium, giving it a hotter outer surface, 9,500 degees than Arcturus at 4,300 degrees. This bright star was the first star other than the sun to be photographed and has served as a standard to which other stars' color and brightness are compared. In its constellation of the Lyre, it sits at the peak of a small triangle connected to a little parallelogram. It's also at one of the vertices of the Summer Triangle it forms with Deneb (DEN-ebb, "tail") in Cygnus (SIG-nus) and Altair (al-TAIR, "swooping eagle") in Aquila (ACK-will-uh).

Between Arcturus and Vega lie the constellations of Corona Borealis and Hercules. Corona Borealis, the northern crown, is fairly easily spotted as a "C" of stars with bright Alphecca (al-FECK-uh) in the place of a gem, giving it a second name, Gemma. Between Corona Borealis and Vega is the heroic figure of Hercules, "the kneeling one" who hangs, head down, in our northern sky. His hips are represented by the asterism of the Keystone as he kneels on one knee with an olive branch in the hand stretched toward Vega and a club held over his head. Though I picture the club as ending at Rasalgethi (ross-al-JAY-thee), the name means "the kneeler's head." It is near the head of the serpent bearer, Rasalhague (ross-al-HAY-gwee) in Ophiuchus (off-YOU-kuss). Ophiuchus spans a dark portion of the sky and includes the asterism of the Coffin, so it takes some time to identify it and the serpant at first. It's worth the effort, particularly if you have a birthday between Nov. 29 and Dec. 17 since the sun is within the boundaries of this (modern) constellation during these days. But don't look for Ophiuchus listed with the astrological signs in the newspaper, as those are not based on modern constellation boundaries. But our symbol of medicine, the Caduceus, may reflect Ophiucus' association with the healer Asclepius.

In the diagram, the ecliptic can be seen below the stick figure of Ophiucus as it passes through the familiar constellations of the Zodiac. Libra was once part of the scorpion and is home to the stars with my favorite names: Zubeneschamali (zu-BEN-ess-sha-MAH-lee), the "northern claw," and Zubenelgenubi (zu-BEN-el-je-NEW-bee), the "southern claw." Next to these, Brachium (BRAY-kee-um), the "arm" is decidedly unromantic!

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The glittering swath of the plane of our galaxy, the Milky Way, is richest in Scorpius and Sagittarius. The center of this whorl of stars roughly 100,000 light-years across lies beyond the asterism of the "teapot," 30,000 light-years away. Near this point is the Lagoon Nebula, a star-formation region, and a small cluster of stars. To find these, make a diamond from the spout of the teapot as shown. Binoculars will reveal a rich array of stars, a telescope will reveal the fuzzy nebula, and a Google search will lead to extraordinarily beautiful images of this stellar nursery. South of this position is the Winter Solstice, the southernmost point of the sun's path.

East of Sagittarius is the constellation of Capricornus, the mergoat. Similar to a mermaid, the goat has the tail of a fish but has the torso of a goat. I must admit having a hard time seeing a goat! What I do see I point out to my students as an upside-down Star Trek communicator, with a shallow "V" inside a deeper one. The stars on the right, Algedi (al-JEE-dee, the "kid") and Dabih (DAY-bee, the "lucky star of the slaughterer" whose identity has been lost in the mists of history) form a line toward Omega Capricorni to form the deeper "V." On the left, the stars Deneb Algedi (DEN-ebb al-JEE-dee, "tail of the kid") and Nashira (NAY-shir-uh, "fortunate one") create a line toward Theta Capricorni to form the inner, shallow "V."

Come July, I hope you will enjoy these sights of the wilderness above from the comfort of a chaise lounge. By then, the wilderness below will be rich with life, filling the night with insect and animal sounds and the strong odor of insect repellant! Once the sun begins its retreat to the south and long, cool nights return to the Adirondacks, look for The Wilderness Above to return to the Adirondack Daily Enterprise.

This has been my first effort at a newspaper column, so I welcome comments, suggestions, and questions from readers. Please email those to me at aodonoghue@stlawu.edu. And look for star parties and lectures given by the Adirondack Public Observatory as we work to make our dream of a public observatory in Tupper Lake into a reality.

 
 

 

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