StarWatch for the greater Lehigh Valley

JULY  2007


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

[Moon Phases]
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Status Current Moon Phase

567    JULY 1, 2007:   Scorpius Dominates the South
I can’t think of anything more exhilarating for a sky watcher then setting off with friends to view the heavens on a star-studded summer’s eve. These types of nights, where the air is clear and dry, are becoming rarer across the US, but they do exist. One of my favorite panoramas of early summer is the southern sky before midnight. If the night is pristine, the diaphanous Milky Way can be seen to descend and expand into the Scorpius-Sagittarius region of the sky before it encounters the horizon. You’ll see brilliant white Jupiter above and slightly to the right of red Antares, the star which marks the heart of the Scorpion. Follow the sleek body of Scorpius downward and to the left as it curls itself into the tail and stinger. Even if trees obscure part of the view, most people can visualize it. To the right of Antares are the three bright and closely spaced stars which delineate the Scorpion’s head. With binoculars, focus upon Antares and you’ll notice just how vibrant its reddish hue becomes. That’s because the eye at night sees mostly with its peripheral rods, and they are not very color sensitive. Average binoculars deliver between 10-30 times more light than the unaided eye, allowing the cones to interpret color. In addition, fainter objects can be seen like the beautiful globular cluster, M4, just to the right of Antares. It appears like a faint round smudge against the darker sky. M4 is an aggregate of over 10,000 stars, distanced from us by about 10,000 light years. That’s small and close. Globulars are much older and larger than the assemblages of stars called open clusters which sustain today’s star generation. Globulars seem to be an aspect of the early evolution of galaxies, perhaps gaining mass through collisions, just like the galaxies have done. Online maps are available at the URL below.

[Scorpius and Sagittarius]
Compare the map above with the photograph below to help locate some of the gems of the southern summer sky. Photography, except where noted, and graphics by Gary A. Becker...

[Scorpius and Sagittarius Photo]

568    JULY 8, 2007:   Here Comes Sagittarius
Last week, I spoke about Scorpius, its reddish heart star, Antares, dominating the southern sky around 11 p.m. It is below and to the right of even brighter Jupiter. From Antares you can follow the body of Scorpius as it curves to the left to form the tail and stinger. To Scorpius’ left lies Sagittarius the Archer. If you witness a centaur, resplendent with bow and arrow drawn to kill his prey, may I suggest therapy; however, if you see a really cool teapot complete with handle, lid, and spout, you’ll be visualizing correctly. Go to the online version of StarWatch at the URL below for maps and photos. One of my favorite open clusters of the heavens, M7, is located between the tail of the Scorpion and the spout of the teapot. If dark enough skies prevail, it is an easy naked eye target, especially if viewed with averted vision. The problem is its closeness to the horizon, only 15 degrees at best, between 11 p.m. and 1:00 a.m. this week. Often M7 goes unnoticed behind trees and buildings, or blends with pockets of horizon hugging light pollution and haze. Use binoculars to spot this gem with stars splattered over a region nearly six times the area of the full moon. Its hugeness is certainly a function of its closeness to Earth, only 1,000 light years distant. M7’s age has been estimated to be 220 million years. You cannot view M7 with binoculars without taking in the bounties of its slightly fainter neighbor, M6, above and to the right. At 1,500 light years from Earth, M6 appears and is actually a more concentrated grouping of stars than M7. It is also about half of M7’s age. Open clusters are sites where star generation is occurring. They differ from the older, larger globular clusters like M4, discussed last week, which formed in galaxies during the rough and tumble early days of the universe.

569    JULY 15, 2007:   Nebular Patches and Star Splotches
Stars splashed against the deep velvet of night... The Milky Way blazing like embers blown in the wind… Ponderosa pines whispering in a warm scented breeze… A shooting star flashing its demise… Then silence, so profound and complete, that it deafens the senses. The conifers rustle again. Drinking in the splendor of a transparent summer’s eve with camera, telescope, and binoculars is one of my favorite pastimes. The memories of earlier encounters coupled with the anticipation of future dark sky rendezvous often provide the balance that gets me through difficult times. This week scan up the backbone of the southern Milky Way starting between the star patterns of Scorpius and Sagittarius which are found low in the south at 11:00 p.m. Bright Jupiter can be seen above and slightly to the left of red Antares in Scorpius. Maps, photos, and past articles will update you on the Scorpius-Sagittarius region of the sky by clicking on “this week’s StarWatch” button found at the URL below. Moving your binoculars northward from M7 and M6, you’ll pass the galactic center of our Milky Way. It is not as impressive a region of sky as most people imagine, because the center of our galaxy is shrouded in thick dust from countless supernovas which hide the stars between our sun and the galactic center. The bottom two stars of Sagittarius’ “teapot” like spout, point in the general direction. Simply double their distance, and you’re virtually there. Move your binoculars slowly from side to side and upwards. If the night is dark and moonless, you will net numerous patches of glowing nebular clouds and scatterings of star splotches, where protostars are contracting, and stellar birth is occurring just like some unknown nebula which contained our sun five billion years ago.

[Scorpius and Sagittarius Photo]
The rich star fields of the southern Milky Way yield a potpourri of nebulas and open clusters where star generation is occurring. Only M4 and M22, two older and larger globular clusters, have not had recent star birth. Scan this area with binoculars on a clear dark summer’s eve to drink in all of it splendor. Digital photography from Bryce Canyon National Park by Gary A. Becker...

[Scorpius and Sagittarius Close-up Photo]

570    JULY 22, 2007:   Gardening on the Moon
Thorny Moon flowers or Moon Roses—gardening on the moon is not as difficult as it might seem. In fact, rakes and shovels are optional. Binoculars or small telescopes will be helpful in revealing large gardened moonscapes from your own backyard whether it is in a city or the country. One fact is certain; these gardened locales get plenty of sunshine, nearly 15 Earth days at a time. As the moon grows or waxes this week, the expansive lunar gardened areas will be revealed more distinctly. By July 29, when the moon is full, they should be at their best. Gardening on the moon deals with the soil. Lunar soil begins to form as soon as any fresh rock is exposed to surface modifications. Cosmic rays, mainly high speed protons and the nuclei of helium atoms, bombard the lunar surface. Like miniature bullets, they tunnel into rocks and weaken their crystalline structures. Likewise expansion and contraction of surface features due to the 500 degree F. temperature variations between day and night, mechanically erodes rock over eons of time. In both cases gravity pulls these broken micro chips downward helping to form the lunar regolith or soil. Meteoric dust collected by the moon as it sweeps through space also sandblasts rock and gradually darkens the lunar surface so that when the moon is pounded by a larger meteorite, the splash of debris exposes the lighter, deeper lunar regolith. These gardened and more reflective areas of the moon can extend for thousands of miles across its desolate, grey surface. The brighter craters and lunar rays (streaks) emanating from these features show where the most recent billion-year old gardening has occurred on one of the slowest evolving bodies in the solar system. Point your binoculars skyward this week, and take a look.

[Lunar Gardened Areas are Brighter]
Gardened regions on the moon appear brighter, indicating that recent events such as meteorite impacts have occurred, churning up the lunar soil. What is recent for the moon? The gardened areas are thoughts to be less than one billion years old. Note the splash marks radiating from 60-mile-in-diameter crater Tycho. This image of the nearly full moon was a public domain photo.

571    JULY 29, 2007:   Perseid's Entice
We have had some uncommonly clear evenings amidst the heat and humidity which is typically considered summer weather. One of these nights, just over a week ago, found friends, Matt and Marcella Gustantino, and me helping Joseph and Rita Scheller of Orefield host an evening under the stars for guests of the Allentown Art Museum. Positioned at strategic locations across the Scheller’s hilltop property, we were looking at celestial wonders which are seldom seen from a near urban environment. One of the highlights of the event was an exceptionally bright meteor which blazed across the backbone of the southern Milky Way. Cries of surprise echoed across the landscape. Later, as I was driving home, I realized that I might have seen a very early member of the Perseid meteor shower. The positioning was correct, from near the top of the constellation of Perseus. Upon researching that fact, I discovered that I was still a few days shy of the onset of this annual celestial spectacle. However, by the time you read this article, Perseids will be flying under unfortunately moonlit skies. Conditions will have improved dramatically by the end of this week with the moon rising closer to midnight. By the beginning of the week of August 5, about a half dozen Perseids will be visible each hour, especially after midnight. By August 10, hourly Perseid rates rise to roughly 15. Meteor rates then climb steadily until maximum night, the evening and morning of August 12/13, when as many as 60 Perseids can be glimpsed each hour during the a.m. The evening of maximum is also the day of new moon, so interference by heaven’s peskiest nightlight will be nil. If you’re going to be looking for Perseids this week, observe overhead, and make sure not to include the moon in your field of view.

[Perseids Maximum-11:00 p.m.]
Perseid meteor rates will increase during the week, especially as the bright moon rises later and becomes less of an interference. Perseids will appear to radiate from a location near the top of the star pattern Perseus the Hero. Rates this week will be low, but often the meteors are bright. This map shows the sky at 11 p.m. looking towards the northeast. Graphics by Gary A. Becker...

[July Star Map]

[July Moon Phase Calendar]