AUGUST  2007

AUGUST STAR MAP | STARWATCH INDEX | MOON PHASE CALENDAR

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Perseid meteor rates will be at their best on Sunday into Monday morning, August 12/13, but good rates will be obtained several days before and after the event. The moon is not a consideration for this year's Perseids which could reach rates of 80 meteors per hour from very dark locations. This map is set for 11:00 p.m. Perseids will be radiating from the red bull's eye on the map. Graphics by Gary A. Becker...

572    AUGUST 5, 2007:   Perseids Could Dazzle

This is the week that Perseid meteor rates build, increasing in quantity each night, while the moon wanes, rising later each morning, ushering in darker and darker skies. If weather conditions are favorable when the shower peaks, Sunday evening into Monday morning, August 12-13, numbers could top 60 shooting stars per hour under moonless, clear, rural skies. Just in case weather conditions don’t cooperate on the best night, good hourly rates of 10 to 20 meteors will be obtainable several days before and after the maximum date. Perseid meteors radiate or diverge from an area near the top of the constellation of Perseus the Hero. Maps are online at the URL below. If you’re out by 11 p.m., Perseus is low in the NE, by 2:00 a.m. about mid-sky in the NE, and by 4:00 a.m. about two-thirds of the distance between the horizon and the zenith, still in the NE. Observing meteors is a cinch, and it’s even more fun in a group. Make sure that you have sleeping bags, pillows, ground tarps, and plastic to cover your gear to protect it from the dew. Snacks and caffeinated beverages will also be a plus if you’re observing for a lengthy period. Lay out facing the NE, but look overhead, since this is normally the darkest region of the sky. Perseid meteors will track back to the top of the star pattern of Perseus. It’s that simple. Perseids are fast—they really zip—and they often are bright, leaving a train or wake, a fluorescent glow where the ablating meteoroid cuts through the atmosphere. Some Perseid trains can last up to 10 seconds or even longer; so they can really be quite impressive. Rates increase during the night with the greatest number of Perseids usually seen in the a.m. just before dawn. If you’re out all night on the evening of maximum, expect to see several hundred shooting stars. Much success!

The Perseid meteor radiant is marked with a bull's eye in this 3:00 a.m. map by Gary A. Becker.

573    AUGUST 12, 2007:   Inspirational Dawn Eclipse

The moon goes courting with the Earth’s shadow on the morning of August 28. If weather conditions cooperate, I’ll definitely be making an effort to see this lunar eclipse because of its interesting visual effects. For East Coast observers, starting at 4:51 a.m., the moon begins to enter the shadow of the Earth. But this is also the beginning of twilight, the time preceding sunrise when Sol is close enough to the horizon to begin illuminating the sky. Keep in mind that the moon will be in the west while twilight is in the east, so as the eclipse begins, the sky will appear completely unaffected by the sun, especially with the illumination of a full moon in the sky. As astronomical twilight, when the sun is between 18 and 12 degrees below the horizon, merges into nautical twilight, about 5:20 a.m., when the sun is between 12 and six degrees below the horizon, the eastern sky will be brightening. The WSW location of the partially eclipsed moon will still be in relative darkness. During nautical twilight the brightest stars are still visible, as well as the horizon. This was the sweet time for navigators to take a positional fix with a sextant on board a ship, long before GPS systems became the routine for determining positional locations. By the beginning of civil twilight, when the sun is less than six degrees below the horizon, and reading a newspaper is now possible, the moon will only be about five degrees above the horizon. Totality, when the moon is completely immersed in the Earth’s shadow, will already have begun several minutes earlier. What makes this eclipse interesting will be the interplay of the brightening sky with the disappearing moon and how long we will be able to see the moon before the brightening sky hides it. Time zones to the west will view the eclipse in a progressively darker sky.

574    AUGUST 19, 2007:   Running with the Shadows of the Night

“We’re running with the shadows of the night… So baby, take my hand; it’ll be all right… Surrender all your dreams to me tonight… They’ll come true in the end.” Remember those really gritty Pat Benatar lyrics of the early ’80s? They came blasting over my car radio as I recently returned from three wonderful nights of dark sky observing at Cherry Springs State Park near Coudersport, PA. Besides making me feel like I was 17, with my whole future ahead of me and ready to be explored, Shadows of the Night reminded me of another shadow chase that will be unfolding over North America on the morning of Tuesday, August 28. Unfortunately, you’ll feel a little older than 17 after watching this lunar eclipse because it will be definitely a sleep robber, starting at 4:51 a.m. on the East Coast and one hour earlier for each time zone to the west. Only West Coast viewers will see the entire eclipse in complete darkness. For the rest of us, this will lead to some interesting photographic opportunities. At some point during the eclipse, the moon will be low in the WSW in a brightening sky, allowing for a combination of land and heavens to be imaged simultaneously. Key ingredients for success are a tripod, an interesting land or cityscape, and critical focus. A cable release to reduce vibrations and a camera with a zoom or telephoto lens to add a little magnification would also be helpful. Set your camera to manual and start with an initial exposure of about 1/50th of a second at F/11, with a film or sensor sensitivity set at ASA 100. Examine the moon for sharpness and correct exposure on your LCD monitor, and vary the time as needed. Examples are posted online at the URL below. Click on “this week’s StarWatch” button. With a little planning and luck you will be “running with the shadows of the night.”

Examples of correctly exposed images of the partially eclipsed moon of March 3, 2007 can be seen here. Read the article for reference exposures. These lunar eclipse images were taken in a completely dark but hazy sky. For the August 28 lunar eclipse, as the light of dawn allows land objects to be seen more distinctly, the partially eclipsed moon may need to be overexposed by a half or whole stop to gain the correct esthetic balance. For time zones to the west where the eclipse will be total and near the horizon during the early segments of dawn, I suggest starting at one to three seconds at F/5.6, ASA 800. Images by Gary A. Becker...

575    AUGUST 26, 2007:   Aurigids to Storm?

On Saturday morning, Earth is set to plow directly through the debris field of Comet Kiess, a long period interloper which circles the sun every 2000 years or so. It was last seen in 1911. Like all comets, Kiess spits out bits and pieces of itself when its travels bring it near the sun. This dross, if intercepted by the Earth in its yearly circuit around Sol, produces a display of meteors or shooting stars. The “if” is the big word. Unlike the August Perseids which are produced by Comet Swift-Tuttle and can be seen for weeks, Kiess’s fragments are contained within an extremely narrow zone. It’s either hit or miss. If we hit the zone precisely, Comet Kiess may produce hundreds of meteors for an hour or so and be much more impressive than the Perseids. But if calculations are just a little off, it could thud like Humpty Dumpty and produce nothing at all. Astronomers P. Jenniskens (SETI Institute) and J. Vaubaillon (Caltech) predict that West Coast observers are targeted for the best performance, and those enthusiasts in the CDT and EDT zones will see zilch. That to me is a little presumptuous. Meteor science as a predictive discipline is even more tenuous than meteorological forecasting. It is in its infancy. So my conjecture for this Saturday morning is to step outside sometime after 2 a.m. and look up. These meteors, called the Aurigids, will radiate from the ENE, just below the bright star, Capella, in Auriga the Charioteer. Aurigids will be bright and swift, so the gibbous moon in the south should not drown them out if you keep Luna away from your field of view. Face north and view the sky overhead to clear obstructions such as trees and buildings. Aurigids have a distinctive yellow color and often leave a glowing trail after they spark.

These three images of the total lunar eclipse of August 28, 2007 were taken from Coopersburg, PA between 5:45 a.m. and 5:54 a.m. using a Canon D20 digital camera and a 200mm zoom lens. Exposures were one second at F/5.6, ASA 800. The increase in the background lighting was the result of a brightening dawn sky. In the last image the eclipse had reached totality, and moon was completely within the Earth's shadow. This was a very bright eclipse. All photos by Gary A. Becker...