The Valley Skywatcher
Volume 38 Number 2
Nassau Observatory - Geauga Park System - 2008
The Valley Skywatcher is the official publication of the Chagrin Valley
Astronomical Society (CVAS), and is distributed to our members and friends.
Bob Modic – Director of Observations – CVAS
Tony Mallama – NASA Goddard Space Flight Center
George Gliba - NASA, Goddard Space Flight Center
Stokes Telescope Records Uranian Satellite Eclipse
Bob Modic and Tony Mallama
The astronomical world has been eagerly awaiting the current equinox of Uranus because it provides an opportunity to record several geophysical and astrometric phenomena under unique conditions of solar lighting and Earth viewing. Observers are imaging the ring plane crossing as well as the first sunlight to the impact the south pole of the planet in 42 years. Photometry of mutual eclipses and occultations by the large uranian satellites, Ariel, Umbriel, Titania, Oberon and Miranda, provides us with an opportunity to measure their relative positions with an accuracy unmatched by Earth-based observers. This precise astrometry can distinguish between two competing orbit ephemeredes, referred to at LA06 and GUST86, that predict different mid-times for the mutual events. We are collaborating with other observers and theoreticians to address the orbit challenge. As reported in the Skywatcher Volume 37 Number 2 several favorable
mutual events are visible from Ohio. The first observation collected by our team comes from Indian Hill where the 16‖ Stokes reflector recorded an eclipse of Umbriel by Ariel on 2007 August 13. The data were taken and reduced by Bob, analyzed by Tony, and are shown in the figure below. The observations clearly indicate that the LA06 ephemeris predicted the time of mid-occultation more accurately than did GUST86. Later this year we will submit the results of our research, including this data and that of several other eclipses and occultations, to a professional journal for publication.
[Figure caption] The observed light curve (dots) was fitted to a synthetic light curve (solid line) which indicates that mid-occultation occurred at UTC 03:05:41 +/- 5 seconds (day fraction 0.1289). The GUST86 ephemeris predicted the mid-
time to be 106 seconds earlier while LA06 predicted it to be only 23 seconds
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The Growing Menace of Light Pollution and More
by G. W.Gliba
Every year the growing menace of light pollution continues. Overall, although there have been some small victories, and a few minor successes, generally the problem of excess night lighting continues. Of course, as we evolved on this great planet, with it's wonderful biological diversity, it is all of nature, including humans, that suffers when ignorant, or worse, careless, humans continue to turn night into day. Not to mention the loss of the sheer beauty of a star spangled night full of stars.
With the 38th Earth Day soon coming on April 22nd, it is a good time to reflect on the natural world that we are an intricate part of. As the late Robinson Jeffers put it: "The greatest beauty is organic wholeness, the wholeness of life and things, love that, and not man apart from that". The more light pollution we have the more we become apart from the world we evolved in. We are of the Earth, and it is way past time to encourage more people to study science more, and start seeing the big picture.
The Universe is way bigger and wonderful than was known only a few years ago. It is estimated that the HST can see about 500 billion galaxies in the observable Universe. And that is only the observable part. It is estimated by some cosmologists that the whole Universe is at least 200 times the size of the small part that we can see. Also, it may well be infinite!
I recently went to an excellent talk on extra-solar planets at GSFC given by the famous extra-solar planet observer Geoffrey W. Marcy, who along with his observing partner R. Paul Butler, at Lick Observatory, have
discovered most of the 250 plus extra-solar planetary systems. In his talk he talked about the famous Drake Equations, on the number of habitable planets in the Milky Way. He was careful to say this was still mostly speculation, but with the new extra-solar planet discoveries, there was some scientific basis now for a more accurate estimate. He was also careful to say the Milky Way only, never mind the Universe. Anyway, it came out to about 10,000 habitable Earthlike planets.
During a question and answer session afterwards, hw was asked about the famous Fermi Paradox, which simply states that if they (other intelligent beings) are out there in large numbers, why haven't we seen evidence for them. Marcy's answer (off the record) was because they are very rare. They are rare in the numbers that occur, or they occur but go extinct.
Earlier, when talking to the well known NASA/GSFC geophysicist, Dr. Paul Lowman, about this, he sited the book Rare Earth by Peter Douglas Ward, which says that complex life may be uncommon. However, he also thought
that the second answer for the Fermi Paradox given by Marcy may also be correct, that they are rare but they go extinct. He said that a way to look at it is that they are like fireflies in the night over geologic time. A chilling outcome and sobering thought indeed!
When faces with the prospects of a runaway green house effect, the loss of biological diversity, and ecological disasters from pollution, not to mention wars, it may be the norm, or typical outcome of a advanced civilization. Light pollution is just one of our follies, but I think an important one. We need to see the stars to see what we are. We are stardust; we are part of Earth. We must put down our ancient alchemy texts and learn the truth using more science before it is too late, if it isn't already.
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North East Ohio Night Skies: The glow of city lights blotting out stars in the
night sky has frustrated many a amateurs, but recent studies have shown that ―light pollution‖—defined as excess or obtrusive light at night—can actually have
serious health effects. Researchers have found that exposure to bright nocturnal light can decrease the human body’s production of melatonin, a hormone secreted at night that regulates our sleep/wake cycles. And decreased melatonin production has in turn been linked to higher rates of breast cancer in women. ―Light at night is now clearly a risk factor for breast cancer,‖ says David Blask, a researcher at the Cooperstown, New York-based Mary Imogene Bassett Research Institute.
Light Pollution and Wasted Energy
Another environmental impact of excessive use of artificial light is, of course, energy waste. The International Dark-Sky Association computes that
unnecessary nighttime lighting wastes upwards of $1.5 billion in electricity costs around the world each year while accounting for the release of more than 12 million tons of carbon dioxide, the leading greenhouse gas, into the atmosphere. Individuals can do their part by keeping lights dim or turned off at home at night—and convincing their employers and local government offices to do the same.
How Light Pollution Affects Birds and AnimalsLight pollution causes other
problems besides increased cancer risks. According to the Sierra Club, birds and
animals can be confused by artificial lighting, leading them away from familiar foraging areas and disrupting their breeding cycles. And the photosynthetic cycles of deciduous trees (those that shed their leaves in the fall) have been shown to be disrupted due to the preponderance of artificial nighttime lights.
Bortle Dark-Sky Scale
The Bortle Dark-Sky Scale is a nine-level numeric (and color coded) measure of the night sky brightness of a particular location. It quantifies the operability of
astronomical objects and the interference caused by light pollution and sky glow.
John E. Bortle created the scale and published it in the February 2001 edition of
Sky & Telescope magazine to help amateur astronomers compare the darkness of
observing sites. The scale ranges from class 1, the darkest skies available on
Earth, through class 9, inner city skies.
Class Title Color limiting Description
Zodiacal light, gegenschein,
zodiacal band visible; M33 direct
vision naked-eye object; Scorpius
and Sagittarius regions of the Excellent dark 1 black 7.6 – 8.0 Milky Way cast obvious shadows sky site on the ground; Airglow is readily
visible; Jupiter and Venus affect
dark adaptation; surroundings
Airglow weakly visible near
horizon; M33 easily seen with
naked eye; highly structured
Summer Milky Way; distinctly
yellowish zodiacal light bright
Typical truly dark enough to cast shadows at dusk 2 gray 7.1 – 7.5 site and dawn; clouds only visible as
dark holes; surroundings still
only barely visible silhouetted
against the sky; many Messier
globular clusters still distinct
Some light pollution evident at
the horizon; clouds illuminated
near horizon, dark overhead;
Milky Way still appears complex;
M15, M4, M5, M22 distinct
3 Rural sky 6.6 – 7.0 naked-eye objects; M33 easily
visible with averted vision;
zodiacal light striking in spring
and autumn, color still visible;
nearer surroundings vaguely
green Light pollution domes visible in various directions over the horizon; zodiacal light is still visible, but not even halfway
extending to the zenith at dusk
or dawn; Milky Way above the
horizon still impressive, but Rural/suburban 4 6.1 – 6.5 lacks most of the finer details; transition yellow M33 a difficult averted vision object, only visible when higher than 55?; clouds illuminated in the directions of the light sources, but still dark overhead; surroundings clearly visible, even at a distance.
Only hints of zodiacal light are seen on the best nights in
autumn and spring; Milky Way is very weak or invisible near the
5 Suburban sky orange 5.6 – 6.0 horizon and looks washed out overhead; light sources visible in most, if not all, directions; clouds are noticeably brighter than the sky.
Zodiacal light is invisible; Milky Way only visible near the zenith; sky within 35? from the horizon glows grayish white; clouds
Bright suburban anywhere in the sky appear fairly 6 red 5.1 – 5.5 sky bright; surroundings easily visible; M33 is impossible to see without at least binoculars, M31
is modestly apparent to the unaided eye.
Entire sky has a grayish-white
hue; strong light sources evident in all directions; Milky Way invisible; M31 and M44 may be
Suburban/urban glimpsed with the naked eye, but 7 red 5.0 at best transition are very indistinct; clouds are brightly lit; even in moderate-
sized telescopes the brightest
Messier objects are only ghosts of their true selves.
Sky glows white or orange--you
can easily read; M31 and M44
are barely glimpsed by an
experienced observer on good
8 City sky white 4.5 at best nights; even with telescope, only
bright Messier objects can be
detected; stars forming familiar
constellation patterns may be
weak or completely invisible.
Sky is brilliantly lit with many
stars forming constellations
invisible and many weaker
constellations invisible; aside
from Pleiades, no Messier object 9 Inner City sky white 4.0 at best is visible to the naked eye; only
objects to provide fairly pleasant
views are the Moon, the Planets
and a few of the brightest star
The Valley Skywatcher
P.O. Box 11
Chagrin Falls, Ohio 44022
Editor: Tom Quesinberry