ARISTARCHUS

L.T.P. RED EVENT

30 OCTOBER 1963

01:50 TO 02:10 UT

This story was reported in Sky & Telescope magazine December 1963 on page 316 and the name of the paper is called A Recent Observation of Lunar Color Phenomena by James A. Greenacre, Aeronautical Chart and Information Center, U.S. Air Force.

"Early in the evening of October 29, 1963. Edward Barr and I had started our regular lunar observations for the U.S. Air Force lunar mapping program at Lowell Observatory. Our telescope was the 24-inch visual refractor, equipped with a zoom lens that gives magnifications from 400 to 1,100. We were also using a Wratten 15 (deep yellow) filter, just ahead of the prism that reflects the image to the eyepiece.

When I started to observe at 6:30 P.M. Mountain Standard Time (1:30 Universal Time on October 30th), I concentrated on the Cobra Head portion of the valley, hoping to refine this area on the chart with additional details. This region of the Moon was under a fairly high solar illumination, as the sun's colongitude was 39º.9. This meant that shadows were short or absent, but the favorable libration permitted us to look into the interiors of the features that we especially wanted to examine.

At first the seeing quality was rated about 2 on a scale of 10. In the next few minutes it improved somewhat, with moments of 3 and 4 seeing during which I zoomed the eyepiece to about 500 power.

At 6:50 p.m.. I noticed a reddish orange color over the domelike structure on the southwest* side of the Cobra Head. Almost simultaneously I saw a small spot of the same color on a hill top across Schroter's Valley. Within about two minutes those colors had become quite brilliant and had considerable sparkle (due perhaps to poor seeing).

I immediately called Mr. Barr to share this observation with me. His first impression of the color was a dark orange. After the Wratten filter was removed the hue remained, but was brighter and sparkled more. We both agreed that at this time the color, seen without the filter, was reddish orange.

Just before removing the filter, I had realized the urgent need to capture these phenomena on film, but I was not yet satisfied that they were real. I felt that taking out the filter would indicate whether or not it was causing some unusual effect. The observation without the filter began to confirm in my mind that changes were taking place, and so it seemed important to scan the entire plateau surrounding Aristarchus.

No other color spots were noted until 6:55 p.m. when I observed an elongated streak of pink along the southwest interior rim of Aristarchus. No other hue could be seen on the inside or outside of this crater. Again Mr. Barr and I observed with and without filter; the only difference seemed to be a somewhat brighter color in unfiltered light. This colored area along the rim of Aristarchus did not sparkle like the other two spots."

REMARKS:

The similarity between this observation and the one reported on 15 July 1989 is remarkable. The colored area on Aristarchus rim is located in the same place. Making me wonder if there is some chemical make up of this part of the crater being a factor. Or if the color of the material on the rim may in some way be reflecting in some way.

"The eyepiece field of view was large enough to have all three areas in sight at the same time. At approximately 7:00 I noticed that the spots at the Cobra Head and on the hill across t he valley had changed to a light ruby red, yet their density and sparkle were still sufficient to hide the surface underneath. I had the impression that I was looking into a large polished gem ruby but could not see through it. Mr. Barr at this time thought that the color was little denser than I had described it, and that it was still retained some reddish orange, but less pronouncedly.

By 7:05 it was apparent that the color was fading. We immediately took our drawing of LAC 39 and outlined the areas these colors covered. I was able to watch the tints at the Cobra Head and the hill top gradually fade until they could no longer be detected at 7:10 and everything seemed the same as before the color phenomena were first noticed. The pink streaks on the rim of Aristarchus were still evident, although fading. They could be seen without filter until they disappeared at 7:15, the rim resuming it normal brightness."

This is a reproduction of the pictured displayed Popular Mechanics November 1964, In article Moon Mysteries Ranger Didn't Solve. The red spots are the locations that Greenacre and Barr marked on their ACIC Lunar Chart LAC 39.

Wide angle view of the Lowell 24" Refractor

The 24" Lowell Telescope used by James A. Greenacre and Edward Barr the night they were mapping the Moon for the U.S. Air Force Lunar mapping program.

Rendition of 11.8 day old Moon on night of event using Starry Night Enthusiast 4.5.

The graph shows the Moon height in degrees during the observation. This indicates it was still rising in the southeast at azimuth 129º, and at a low enough altitude that the color effect could have been caused by Earths atmosphere and thus be a spurious color event. When examining the Moon elevation for the 15 July 1989 and 14 June 1987 all three the Moon less than 35 degrees in elevation in the sky.

When examining the perigee and apogee data I found that this event took place two days prior to closest perigee for the year. This would be a strong indicator that tidal stress may be a factor causing possible out gassing to place and then have a florescence of this gas by the Solar plasma. Data was taken from the Lunar Perigee and Apogee Calculator at web site: http://www.fourmilab.ch/earthview/pacalc.html

SOLAR TERRESTRIAL ACTIVITY REPORT

When you examine the solar data for night of 29/30 October 1963 one finds that the Planetary A Index was very active that night. Also the sunspot activity was also on the increase.