For
the amateur astronomer, the Moon has always been a favorite target. In
fact, until the advent of the space program, amateurs dominated the field
of selenography (the study of the physical features of the Moon). Now,
with the impact of a great multitude of photographs taken at close-hand
one might assume that the work of the amateur has been made insignificant.
Too many people have gotten the idea that no awe and mystery remains about
our "Queen of the Night."
Such is not the case! Many areas of lunar observation remain the forte of the amateur astronomer, fields that may be pursued without threat of obsolescence. Unlike the professional, the amateur is blessed with the freedom to scan a lunar feature of his choice for extended periods of time in order to study details under varying lighting conditions. The professional simply does not have the budget to do this. In order for the results of any observing program to be useful, its participants must use a blend of preparation, skill, patience, and tenacity. Because of the large image size and brightness of the Moon, lunar studies are especially suited for amateurs using small to moderate apertures. More important, there have been numerous instances of professional astronomers, enlisting the services of amateurs. Fortunately, amateurs are able to come to the rescue by monitoring the specific regions of the Moon under the conditions sought by professionals. In a few cases, the needed data already existed in the archives of amateurs. Such cooperative efforts clearly demonstrate how meaningful amateur observations of the Moon can be. The lunar efforts of the ALPO are divided
into several specific programs. Each has its own coordinator. There is
also a coordinator who collects observations that do not fit into any of
these categories. Lunar Transient Phenomena (LTP)One example of an interesting research program open to amateurs is the search for Lunar Transient Phenomena (LTP). Transient phenomena are variations on the lunar surface that are transitory ¾ not seen during each lunation. The release of gasses, shifting of surface rocks or the movement of sub-surface strata could cause such phenomena. Systematic, simultaneous studies by teams observers is especially worthwhile, since LTP events might be glimpsed for only a few seconds. Our goal is to differentiate between LTP "reports" and bona fide LTP events. The literature is replete with historical accounts of LTP. There have been reports of temporarily disappearing details, rapidly changing colors, and even the disappearance of whole craters! While most of these reports turn out to be highly questionable, there are growing numbers of undisputedly authentic LTP events. Some have been observed simultaneously by distant and independent observers. As procedures have been refined and improved over the years, it has been possible to confirm some LTP events photographically or with CCD techniques. Of the more than 1,500 LTP reports and events catalogued since the year 557 A.D., perhaps the widely publicized Alphonsus spectrograms of Kozyrev in 1958, the observations of Greenacre and Barr of Aristarchus in 1962, and the Project Moon-Blink reports of the 1960's, are the most familiar. There are many regions on the lunar surface, which have been suspected of LTP events.
From the information on hand to date, it
might be concluded that LTP events are probably of random internal origin
and are only weakly attributable to external influences. Perhaps many
causative factors operate together to give the strong sunrise correlation.
Supporting this tentative conclusion of an internal origin is the
distribution and association of many LTP sites with volcanic maria,
dark-haloed craters, sinuous rills, and lunar domes. The Lunar Selected Areas Program (SAP)In addition to the short-lived LTP events, observers are encouraged to monitor certain selected lunar features suspected of "seasonal" or long-term variations. An example of this would be a variation in the tone or hue of a given area, which cannot be attributed to varying solar illumination and which does not repeat systematically from lunation to lunation. These tonal changes usually occur where dark radial bands or dark haloes are seen within or around craters, or where darker regions exist within brighter areas on the lunar surface. In many (but not all) cases, unusual changes in the overall size and shape have been detected in conjunction with tonal or color fluctuations. Such features include Alphonsus, Aristarchus, Eratosthenes, Herodotus, Kepler, Messier-Pickering, Plato, Atlas, Ross D, Hell, Pico, Piton, and Colombo. An observational baseline of many years is needed. Regular and careful monitoring will familiarize the observer with normal, yet often complex, changes that features undergo from lunar sunrise to sunset, and it will be possible to recognize anomalies more readily. No special artistic talent is necessary, nor is exceptional visual acuity. The most fundamental and essential prerequisite is the willingness to follow the Moon and the chosen features for many consecutive lunations, year after year. Scientific objectivity is mandatory, for the observer must develop a constant practice of recording precisely what is seen at the eyepiece, not what one might expect to see. Should there be any doubt whatsoever about what is perceived, the observer must make a note of this. The resulting data will be far more reliable and of lasting value. Although there is no minimum size telescope
required for participation in this program, larger the aperture the
better. However, at least a 4” refractor or 6” reflector should be
sufficient. The driving factor in choosing a telescope should be optical
excellence. The observer should be sufficiently familiar with his
instrument to recognize scattered or reflected light, irradiation, as well
as aberrations caused by the eye, the instrument, and the atmosphere. The most frequent anomalous phenomena
observed are:
Most of these phenomena are anomalous variations in shape, tone, or color, which cannot be attributed to changing solar angle, and which do not repeat from lunation to lunation. The lunar features that are currently under study by the SAP are:
These
areas were chosen because they are easy to find, and have been suspected
of anomalies in the past. Complete outline charts and observing forms are
available from the Lunar Section for each of these features. Lunar
Meteoritic Impact Search Section
Lunar
impact observations is an important area of research for the amateur.
A lack of abundant annual showers coupled with unfavorable
weather in many places has limited the opportunity for this work in recent
months. However, there have
been a few observers who monitor the moon monthly for impacts from
interplanetary debris, with the most recent unconfirmed event occurring on
September 11, 2002. The
two showers of note over the past year were the Leonids of 2001 and the
Perseids of 2002. Many observed during these events, and many candidates
were produced. The Perseids
produced over 55 candidates, a few of which were probable impact events,
but there have been no confirmations as of this writing. The Leonids
produced nearly 50 candidates, 2 of which are confirmed, and at least 5 of
which are probable. Two
research groups have observed the Leonids in 1999 and 2001, and their
results have raised the total number of confirmed impacts to 15. In light
of these results, and to better qualify the probability of an observation
being a true lunar impact the section has, as of October 2002, adopted a
new and more definitive classification scheme. Observers are encouraged to
use these terms, to the best of their knowledge, in describing their
observations.
With
these criteria in place, we can better group observations in terms of
quality and estimate the likelihood of the observation being that of an
actual impact event. It is
very possible that a candidate could be elevated to the status of
"confirmed" with the corroborative observation of a second
independent observer. The Coordinator has submitted a NASA proposal to systematically study the lunar impact phenomena with ten specially equipped observers. If the proposal is funded, the need for supporting observers (with their own equipment) will increase.
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Rare
and elusive as they may seem LTP events do appear to fall within roughly
defined categories. Small, temporary reddish or pinkish patches,
presumably due to fluorescence of incandescent gases, have been noted
shortly after lunar sunrise, while glows lacking any distinct hue have
been noticed, sometimes seen on the night hemisphere of the Moon. Emerging
quite instantaneously or lasting for several minutes have been bright
points of light near the lunar terminator or on the darkened hemisphere of
the Moon, while rapid fluctuations in the brightness of a specific area
have been occasionally recorded, again most often in the early lunar
morning. Obscurations, visible directly as "fogs" or
"mists", or indirectly by concealing or obliterating known
surface features, are also frequently associated with times of lunar
sunrise. Many variations have been reported in Earthshine conditions or in
conjunction with partial or total lunar eclipses.