StarWatch for the greater Lehigh Valley

JULY  2008


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

[Moon Phases]
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Geomagnetic Field:  
Status Current Moon Phase
620    JULY 6, 2008:   One More Book
“No more books,” I emphatically stated to my wife as she inquired what I might be interested in receiving for my birthday. “I’ve just got too many of them.” “Fine,” she said, and I honestly thought that was going to be the end of it. The next day, I found myself rummaging around the dinning room surveying the piles of papers that had to be cleaned up over the summer break. My wife, Susan, is a senior high English teacher with a staggering amount of paperwork to correct from September through June. My eye caught a book with an orange star cluster on its front cover and titled Universe: The Definitive Visual Guide, ISBN 978-0-7566-3670-8, DK Publishing, 2008, $24.95. “Another pretty book,” I mused, “filled with NASA images but little substantive text.” I picked it up. It was heavy with the slight bouquet of printer’s ink which led me to believe that it was a quality product. When I opened Universe to a random page, my eyes were met with a cornucopia of exquisite images on black paper, diagrams, and charts, each with its own caption, telling a snippet of information, which in this case was about comets. I turned the page, and now the paper was white with black text. Most of the pictures were of comets that I had actually seen, well not the Great Comet of 1680, and again, each of the 50 to 150 word captions highlighted a different aspect of cometary astronomy. I snuck the book downstairs into my study for further examination and found the information to be well-written, concise, and completely up-to-date. It should be because its general editor, Martin Rees, is Astronomer Royal of the UK. When I showed the book to my wife, she smiled and said, “Happy Birthday.” I said, “I’ll definitely take it.” I have since ordered 60 additional copies for my astronomy students this fall. Thanks, Sue. I am once again humbled.

[Mar-Regulus-Saturn-moon Conjunction]
From right to left, the moon, the star Regulus, Mars, and Saturn line up on the misty evening of July 5. It had rained several hours earlier. The 30 second guided image was taken with a Canon 40D camera, ASA 640 with a zoom lens set at an effective focal length of 112mm, F/2.8. Conditions were so hazy near the horizon that the moon was not visible to the unaided eye. The image was color corrected to subtract the effects of a nearby sodium vapor lamp. Gary A. Becker photo from Coopersburg, PA...

621    JULY 13, 2008:   The Moon Illusion
This is a great week to watch the moon blossom in brightness as well as approach and pass the bright planet Jupiter low in the SE. It is also a great week to partake in an experiment which is called the Moon Illusion. Everyone has seen a full moon on the horizon and made the comment about its size. When the moon is near to the horizon, it appears much larger than when it is higher in the sky. Actually, you can prove that the moon really does not change in size by holding a dime at arm’s length and using it to cover the moon when it is in a rising position. The fit should be tight. Wait a couple of hours until the moon has gained altitude and appears smaller. Repeat the experiment, occulting the moon with the dime, and you will notice that the fit will be just as tight as when the moon was close to the horizon. What is happening to convince the mind that the moon appears larger when it is nearer to the horizon is a conflict between the rational and intuitive parts of the brain. The intuitive brain sees the sky as a flattened dome, believing that objects closer to the horizon are considerably farther away than objects which are located overhead. Puffy clouds in a blue sky offer a good example of this effect. Clouds nearer to the horizon are farther away and appear smaller and more foreshortened than clouds which are above the observer. This mindset of our intuitive brain is transferred to our perception of the sky at night. Because the moon is far away in comparison to the clouds, birds, and planes of the sky, the moon’s size basically does not change. Our rational brain perceives no alteration in the size of the moon whether it is near the horizon or high in the sky. This cerebral conflict causes the brain to interpret the horizon moon as closer, and therefore, larger in size. See the Moon Illusion in the diagram below.

[Moon Illusion]
The Moon Illusion is created by a conflict between the intuitive and rational parts of the brain. It can be depicted with an inverted Ponzo illusion as shown above. All four moons are the same size, yet on the left, the lower moon nearer to the horizon appears larger than the higher moon. Scroll the picture back and forth and see if you don’t agree. Read the article above to find out why. Gary A. Becker design from original photography...

[July 10, just after First Quarter]
Although this image was taken on the day of the first quarter moon, July 10, it was taken nearly 22 hours after quadrature as it can be seen by the slightly bulged terminator. Conditions were hazy. Gary A. Becker photo from Coopersburg, PA, equatorially mounted Canon 40D, EFL 640mm, F/8, 1/100s, ASA 400...

[July 14 moon]
The moon July 14 and July 16... Conditions were clear. Gary A. Becker photos from Coopersburg, PA, equatorially mounted Canon 40D, EFL 800mm, F/8, 1/125s, ASA 200 (July 14); 1/100, ASA 100 (July 15)...

622    JULY 20, 2008:   Bright Light in the Southeast
Is it Christmas in July? What is that bright star low in the SE after sundown? If you live where I live in Coopersburg, PA, then it even points in the general direction of Bethlehem—that’s Bethlehem, PA. Currently, with Venus too close to the sun for easy viewing, it is the third brightest object in the sky. By Jove, if you’re thinking Jupiter, then you are right on target. Jupiter is not only the largest and most massive of the eight planets in our solar system, but it has influenced our neighborhood in space second only to the sun. In fact, because of its large gravitational attraction, Jupiter, and to a lesser extent Saturn, have helped to cleanse and protect the inner solar system from the myriad of comets that are sent sunward by other stars passing close to Sol. We witnessed this “Jupiter Effect” in July of 1994 when Comet Shoemaker-Levy 9, first broken into 21 fragments by Jupiter’s strong gravitational field, slammed into Jove to produce the best solar system fireworks ever witnessed by humankind. This same gravitational field holds 63 moons in its grasp. Most are small, captured asteroids that wandered into Jupiter’s influence, but its four largest satellites, Io, Europa, Ganymede, and Callisto, create a solar system in miniature, depicting changes in composition and size which reflect what we see happening in our own planetary landscape. The inner solar system is composed of smaller, denser worlds which are composed of materials that have higher melting and boiling temperatures. The same can be said about Io and Europa. Outer moons, Ganymede and Callisto, are larger, less dense, and composed of ice and rock. The outer four planets of our solar system are larger, more massive, and made up of matter with a lower melt-boil temperature. I’ll talk more about Jupiter next week.

[Jupiter and moons]
Jupiter and its four Galilean satellites were combined to produce this composite image taken on July 20 at 12:44 a.m. EDT. From left to right: Ganymede, Europa, Io, Jupiter, and Callisto. Note the detail visible in Jupiter’s atmosphere in this single image, as well as the differences in brightness of Jupiter's satellites. Canon 40D, combined with a Nikon 500mm, F/8 lens, and 2X Nikon extender for an EFL of 1600mm at F/16... The Galilean satellites were imaged for 3.2 seconds, ASA 400, while the image of Jupiter was snapped at 1/15 second, ASA 400... Gary A. Becker photography from Coopersburg, PA...

[Waning gibbous moons]
Waning Gibbous Moons, 96.6 percent sunlit (left) and 85.2 percent sunlit:   These photos were taken at 12:34 a.m. EDT July 20 and 1:23 a.m. EDT, July 22, with a Canon 40D camera on an equatorial mount, attached to a 500mm, F/8, Nikon lens (EFL 1600mm, F/16) at 1/20 second, ASA 360. The image below this one, was taken from the July 22 picture. Conditions were very hazy. Gary A. Becker images...

[Waning gibbous moon]
This image of the waning gibbous moon focuses on the Southern Highlands which are very heavily cratered. It is an enlargement of the above image. The bright crater on the far left of the photo is Tycho, which is about 53 miles in diameter. Gary A. Becker image from Coopersburg, PA...

[Last quarter and 24 day old moon]
The last quarter moon (left) and 24 day old moon:   The next two images below were enlargements taken from the pictures which are seen here.. Gary A. Becker, Coopersburg, PA...

[Last quarter moon]
The last quarter moon shows a wealth of detail in the southern hemisphere. The crater Tycho seen as the bright feature towards the left in the picture above, is now upper center ready to be submerged into a two-week lunar night. An equatorially mounted Canon 40D camera, attached to a 500mm, F/8 Nikon lens with a 2X extender for an EFL of 1600mm, F/16, was used at 1/30 second, ASA 360. Gary A. Becker image, taken on July 25, 4:26 a.m. from Coopersburg, PA...

[Waning crescent moon]
The 58 mile-in-diameter crater, Copernicus, dominates this image of the northern lunar hemisphere taken on July 26, at 4:48 a.m. Above Copernicus is the Imbrium basin the largest impact feature on the moon. Connected to Imbrium is Sinus Iridum, the Bay of Rainbows. To Copernicus’s left is Oceanus Procellarum. An equatorially mounted Canon 40D camera, attached to a 500mm, F/8 Nikon lens with a 2X extender for an EFL of 1600mm, F/16, was used at 1/25 second, ASA 360. Gary A. Becker image from Coopersburg, PA...

623    JULY 27, 2008:   Fun with Jupiter on Hazy Summer Nights
Where I live in eastern PA, the white and hazy skies of summer have taken over. If you’re into astronomy like I am, but with only 20 stars visible from your backyard, what possibly can you do? As a kid, I would have just sulked, but older and hopefully a bit wiser, there’s still adventure in even a milky sky. Jupiter, that bright star like object shining with an even light in the SE after dark, presents a wealth of astronomical changes that can be fun to witness. Because of its brightness, Jupiter can act as a frame of reference for the motion of other objects. Take, for instance, the Earth. If you place Jupiter within the upper part of a tree so that it can appear and disappear among its smallest branches, you can watch the Earth rotating on a windless night. All you have to do is hold your head very still, and you’ll perceive the slow but irreversible westward march of Jove. Earth’s yearly revolution around the sun changes the sun’s position against the background of stars, causing celestial objects to cross the same point in the sky about four minutes earlier each evening. Place Jupiter over a telephone pole or a streetlight, let’s say, at 10 p.m. Come back to the same location at the same time several days later. You will notice Jupiter to the right of its original position, mainly because of the Earth’s orbital motion. With binoculars, a spotting scope, or ever better still, a small telescope, Jupiter’s nightly motion against more distant background stars can be witnessed. Presently, Jupiter is moving towards the west or retrograding in the sky. Even more interesting are the orbital motions of Jupiter’s four largest satellites: Io, Europa, Ganymede, and Callisto. They are endlessly changing positions as they circle Jove. Online photos of Jupiter and its moons are available at the URL posted with this article.

[Jupiter and moons]
This composite of Jupiter, along with three of its Galilean satellites, was taken at 12:18 a.m. EDT on July 16. It is compared to a computer mockup at the same time. The moons were photographed for 3.2 seconds. Jupiter, snapped at 1/100 second, was superimposed over the overexposed image of Jove containing the satellites. Gary A. Becker image from Coopersburg, PA, equatorially mounted Canon 40D, 800mm EFL, F/8, ASA 100.

[Conjuction of moon and Jupiter]
Wide Conjunction:   Jupiter and the moon say hello on the morning of July 17. Gary A. Becker image from Coopersburg, PA, equatorially mounted Canon 40D, 112mm EFL, F/8, ASA 100... Exposure length for the moon was 1/100 second, while Jupiter was recorded in a separate image for 3.2 seconds.

[Jupiter and moons]
Gary A. Becker photography...

[27 day old moon]
A 27-day old moon greets me above the treetops of my backyard during twilight (5:06 a.m. EDT) on the morning of July 29. An equatorially mounted Canon 40D camera attached to a Nikon 500mm, F/8 lens with a 2X extender was used for this 1/13 second, F/16, (EFL 1600mm) image at an ASA of 400. Gary A. Becker image from Coopersburg, PA...

[July Star Map]

[July Moon Phase Calendar]