ALPHONSUS

13.4S by 2.8W

LUNAR TRANSIENT PHENOMENA

HISTORY

DAVID O. DARLING

"Alphonsus is 70 miles in diameter and its walls are very broad and complex. It has a central mountain about the height of Vesuvius, which is part of longitudinal ridge. The floor is full of interesting detail, among which are some dusky spots that are most prominent under a high light. They are said to 'variable'. Three of these spots are on the west part of the floor and are connected by winding cleft. A fourth larger triangular spots abuts on the east wall. There are over 50 craterlets on the interior. On the evening of November 3, 1958, the Russian astronomer N. A. Kozyrev was observing the central mountain of Alphonsus using the 50-inch reflector of the Crimean Astrophysical Observatory and witnessed what appeared to be some kind of volcanic activity there." The Moon Observer's Handbook by Fred W. Price.

Lunar Orbiter 4 Photograph. NASA

"The lunar crater Alphonsus occupies a special place in the literature of lunar surface happenings because something that was observed within its walls during November, 1958, was the only really well authenticated example of TLP at that time. Local events had been reported inside Alphonsus previous to this. As far back as 1882, Klein asserted that there was volcanic activity inside Alphonsus, but the reliability of this report may be questionable. A more recent report is the photographic observation made by D. Alter, in 1955. He photographed Alphonsus and Arzachel with the 60 inch Mount Wilson reflector in both infra-red and ultra-violet light. As is well known, infra-red wavelengths penetrate haze and mist whereas ultra-violet is scattered by it. On many occasions, Altar found that in ultra-violet light pictures, the cleft on the west part of the floor of Alphonsus looked blurred. whereas the effects were not seen in the red light pictures. Altar cautiously suggested that the blurring effect in the violet light could be due to light scattering by a temporary or permanent atmosphere on the floor of Alphonsus, possibly an emission of gas from the clefts. Then on night of November 3/4, 1958, the Russian astronomer N. A. Kozyrev was using the 50-inch reflector of the Crimean Astrophysical Observatory to take spectrograms of Alphonsus. He was doing this as a result of a suggestion of P.A. Moore to him and other observers that they keep Alphonsus under close scrutiny. Because the 50-inch reflector did not have a guide scope, Kozyrev had to watch it through the main telescope and guide it during the photographic exposure. On this occasion, the spectrograph slit was centered on the central mountain of Alphonsus. As he watch Kozyrev noticed a blurring of the central peak of Alphonsus at 01.00 UT, which seemed to have become enveloped in a reddish fog. Later, at around 03.00 UT, the central peak became unusually bright and suddenly fade. By about 3.45, Alphonsus resumed its normal appearance. During this time, Kozyrev had exposed several photographic plates and that taken between 03.00 and 03.30 was uncommonly interesting. This and others indicated that hot carbon gas had been ejected, which caused the temperature to rise to 2000° C. Although this conclusion was doubted by some other theorists, there is no doubt that some kind of disturbance had occurred in Alphonsus and that Kozyrev had witness a TLP." The Moon Observer's Handbook by Fred W. Price.

Drawing by N. A. Kozyrev of out gassing.

When looking at the graph below we can see that lunar transient phenomena events do not start until the sunrise terminator begins it approach to Alphonsus. The most active days are from age 6 to 10 days. The next most active day is on 22nd day of lunation.

When looking at lunar transient phenomena by type the two most active are brightening and reddish events. The reddish event as you may recall is the main event that was documented by Russian Astronomer N. A. Kozyrev.

When looking at the lunar transient phenomena reported by months of the year the two most active months are April and November. This is much different than the graph showing the total L.T.P. by month, the two most active months are July and October.

The following drawings of Alphonsus were done by me to show the different aspects the crater takes under changing solar illumination. This drawing shows the central peak to be casting its spear like shadow across the crater floor. As you will recall this central peak was the source of the out gassing observed by Russian astronomer N. A. Kozyrev.

This drawing was done while viewing the image from video camera, this allowed me to put more time into the drawing than one normally could do due to restrictions such as fatigue and being harassed by mosquitoes. There were many subtle shading going across the crater floor. I also noted different points of the crater with albedo measurements taken during the drawing. The crater Alphonsus is truly a remarkable crater to study and recommend to all observers to study this formation well.