JULY  2006

JULY STAR MAP | STARWATCH INDEX | MOON PHASE CALENDAR

Print Large Sky Charts For 10 p.m. EDT:   NORTH | EAST | SOUTH | WEST | ZENITH

 

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515    JULY 2, 2006:   The Sky in July: Looking North

For the next five weeks we will be taking an informal tour of the summer sky. I’ll keep you abreast of current events while focusing on one of the four cardinal directions, including the sky overhead. A complete series of maps for 10 p.m. in color and printable black and white can be found with this month’s series of StarWatch articles at the URL below. You can still catch Mars and Saturn very low in the WNW this week, about 9:30 p.m. From lowest to highest, Saturn, Mars, and the bright star Regulus, of Leo the Lion, will form nearly a straight line with Saturn, the brightest of the trio. Mars is the faintest. Use binoculars. In the north, the Big Dipper is already cup down—handle up, a sure sign of its impending lower culmination and the cooler days of autumn which will follow. The star, Polaris, around which the northern heavens pivot, can be easily found by following the Pointer Stars (lowest) of the Dipper’s cup, Dubhe and Merak, to the right. Its importance results not from its brightness, but rather from its stationary position, marking the direction north. Above Polaris are the second and third brightest stars of the Little Dipper, Kochab (left), just a tad 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. Bisecting a line between Kochab and Pherkad to Mizar, the middle star of the Big Dipper’s handle brings you to a pair of stars in the tail of Draco the Dragon. The brighter member is Thuban, the north star of Ancient Egypt. The Earth’s axis wobbles in a giant circle over 25,800 years. Currently, it points to Polaris, but by 14,000 AD, Vega, in Lyra the Harp will be our pole star.

Looking North at 10 p.m.:  Observe near the beginning of the week when moonlight will be less bothersome. Graphics by Gary A. Becker and The Sky, level six...

516    JULY 9, 2006:   The Sky in July: Looking East

This week, turn your head east to examine the rising summer stars. Facing north, hold your arms out and say “WE.” West is to the left as is the letter “W” in “WE,” and east is to the right. You can also face north and recite this mnemonic, “North Never Eats Soggy Waffles,” making sure that after the second “N,” you spin a quarter turn in a clockwise direction for each word. By mid-July at 10 p.m. from a rural setting, the summer Milky Way is arched across the eastern sky like a diffuse whitish haze with a cotton candy texture. This view, which could be witnessed by nearly everyone three to five generations ago, has almost disappeared because of the bubbles of light spreading outward from our urban centers. There is a trick to knowing where the Milky Way is located even if the lights of a town or city are hiding it. On a clear mid-July night by 10 p.m. the eastern sky will be dominated by three bright stars which form the famous asterism of the Great Summer Triangle. The brightest of the triad is Vega of Lyra the Harp, 25.3 light years away. Below and to the right is the faintest of the three, Deneb situated at a staggering 3,230 light years from the sun. It is the brightest star for its distance in the night sky. Below and to Vega’s left is Altair of Aquila the Eagle, 16.8-light years distant. During some of the muggiest nights of August, these three stars can often be the only ones to pierce the hazy air. So where is the summer Milky Way? The galactic equator passes through the Great Summer Triangle just below Deneb and about 10 degrees above Altair. Scan with binoculars from Vega downward, and you’ll see the density of luminaries increase as you encounter the rich star fields of the Milky Way. Follow the Milky Way southward, and you’ll be ready for next week’s discussion.

Looking East at 10 p.m.:  Wait until the end of the week when moonlight will not interfer. Graphics by Gary A. Becker and The Sky, level six...

517    JULY 16, 2006:   The Sky in July: Looking South

Looking south in mid-July at about 10 p.m. under a rural sky is truly one of the great delights of summer sky watching. Arched across the vault of the heavens will be the ethereal blush of the Milky Way’s star clouds. I never truly appreciated the concept of star clouds until I viewed our galaxy from Australia in 2001. Through binoculars their meaning became apparent—sheets of stars billowing out like thunderheads—tens of thousands of tiny pinpoints registered on the canvas of my eyes. Unfortunately, these pristine views are becoming rarer to attain because of increased urbanization and light pollution. Still, finding a hilltop with a flat southern exposure, even in suburbia, will allow you to view Scorpius, the killer of Orion, and to the Scorpion’s left, Sagittarius, the Archer. Identify Antares, the Scorpion’s brightest star, due south at 10 p.m. To Antares’s right is brilliant Jupiter in the SW. At 600 light years distant, Antares, a red supergiant, will twinkle and appear ruddy through binoculars in contrast to Jupiter’s steadier, white light. The stars below Antares form a hook which represents the body and tail of the Scorpion. Three stars above and to right of Antares form his head. To the left of Scorpius lies Sagittarius the Archer, better known for its teapot-like shape, created by its brighter stars. The teapot in mid-July at 10 p.m. is parallel to the horizon; but as the night waxes, it dips into the SW, its spout tipping forward, a pleasant reminder that summer nights can be cool and that hot beverages are still in order. Gazing just above the Teapot’s spout directs your eyes towards the center of the Milky Way, about 28,000 light years distant. A binocular sweep in the immediate area will reveal some of the best clusters and nebulae of the summer.

Looking South at 10 p.m. in July is about the best time to see the center bulge of our Milky Way Galaxy. A very clear sky, a good southern exposure, and a rural location are necessary conditions to accomplish this feat. Graphics by Gary A. Becker and The Sky, level six...

518    JULY 23, 2006:   The Sky in July: Looking West

Late July inaugurates a period of about three weeks when meteor rates begin to climb. The kickoff results from the activity of about a half dozen smaller meteor streams in combination with Delta Aquarid meteors which max during the morning hours of Friday and Saturday. Hourly rates of 10-15 shooting stars can be expected. Your best results will be obtained by observing overhead from a rural setting after 3 a.m. Mixed in with the lot of mostly fainter meteors may be several dazzling fireballs, signaling the beginning of August Perseid activity, the best known and observed meteor event of the year. I’ll be talking more about the Perseids in several weeks. Because of the new moon on Tuesday, this week is also favorable to continue our tour of the 10 p.m. sky. Check out Jupiter in the SW as darkness falls. It will be the brightest sky object until the moon gains prominence early next week. Last month, Jupiter was nearly due south during evening twilight. By late August, Jove will be setting by 10:00 p.m. To Jupiter’s right, and considerably lower in the sky, will be Spica, the brightest star of Virgo, the Virgin. Although its low altitude may betray its hot, blue-white color, it is producing energy at a rate of nearly 2,200 times the output of our sun. Above Spica, in the West about midway up in the sky, will be Arcturus, the third brightest luminary in the nighttime heavens. Although Arcturus appears 2.6 times brighter than Spica, it is actually generating only 1.5 percent of Spica’s total energy. This conundrum between energy output and brightness becomes clearer when the distances to these stars are compared. Powerhouse Spica is nearly 900 light years distant, while Arcturus is only 36.7 light years from the sun.

Looking West at 10 p.m.:   Follow the “arc” of the handle of the Big Dipper to the star Arcturus, and continue onward to “spike” Spica. See the article above. Graphics by Gary A. Becker and The Sky, level six...

519    JULY 30, 2006:   The Sky in July: Looking Overhead

This week, our tour of the summer sky focuses overhead where the stars shine at their brightest. The zenith offers the least amount of atmosphere that light must penetrate, enabling observers in hazy and light polluted areas their best chance of seeing the nighttime sky. View overhead while facing the east, and you’ll notice the three bright stars of the Great Summer Triangle, the sentinels of the season of short nights. Often, the GST will be the only three stars conspicuously visible during the hot, humid nights of summer. Vega, the fifth brightest star of the night, is the most vivid of the triad and at 10 p.m., the luminary that is closest to the zenith. Looking north, you’ll see the four stars of the quadrilateral that forms the head of Draco the Dragon. It is twice as high in the sky as the North Star. The head of the Dragon will fit comfortably within the field of view of most standard binoculars. Face west. The Big Dipper will be to your right and Jupiter to your left. The yellowish, bright star, mid-sky, will be Arcturus of Bootes the Herdsman. It is the third brightest star of the night. Above it will be a cup-like grouping of stars called Corona Borealis, the Northern Crown. Most, if not all of the stars from this grouping, should fit within a binocular’s field of view. If you follow this little exercise, you will have discovered the three markers—the star Vega, the head of Draco, and Corona Borealis—which should allow you to find Hercules the Strongman within its triangular structure. Hercules’s stars are about as bright as the faintest luminary of the Big Dipper, Megrez, the star closest to the handle. If you can find the four stars of the “Keystone” in Hercules, you’re there. Print the online map posted with this week’s StarWatch to make it easier.

Looking overhead at 10 p.m.:   Hold the map overhead and face the direction that you are interested in viewing. Graphics by Gary A. Becker and The Sky, level six...