EARTHSHINE OBSERVATION
ARISTARCHUS VISIBLE TO THE NAKED EYE
29 MAY 1979
02:50 TO 02:57
By
David O. Darling
Tonight I set up the 12.5 f5 Newtonian reflector to view the 3.003 day old Crescent Moon hanging low in the western sky. It was some 25 minutes after I had begun observing when I saw a bright blue glowing patch on the western side of the Moon. This area was bathed in earthshine so you could see different craters and lunar Maria. After watching this area get brighter and brighter I found that it was located exactly in the same spot as the crater Aristarchus. The one crater that is famous for such events of Lunar Transient Phenomena.
Made Using Starry Night Enthusiast 4.5
Rendition of Moon on night of observation located 8º above the western horizon.
I first observed the glow at 9:50 P.M. 28 May 1979 CDT or 02:50 UT on 29 May and the glow had all but diminished by 9:57 P.M. CDT or 02:57 UT . The brightness was about 2nd to 3rd magnitude and electric arc blue in color and was glowing with such intensity that I could see it with my naked eye. The size of the glowing patch I estimated to be about 50 square miles. The glow was also so intense that the glass of the eyepiece was glowing the same color electric arc blue.
Rendition made using Reading Information Technology Inc (RTI) showing appearance of Moon and glowing spot.
At the onset of this event I had called my wife Edna, to come out and witness this event. By the time she arrived it had decline in intensity but she could still see it through the telescope eyepiece with relative ease.
I have never witness in my 16 years of doing astronomy the kind of phenomena I saw tonight, it was the most amazing 7 minute light show I have ever seen even now 25 years later.
SOLAR TERRESTRIAL ACTIVITY REPORT
When examining the solar data for this time period 29 May has increased Planetary A activity and increased sunspot activity. This could be a factor for the event since it behaved like a gaseous medium could be excited by the solar plasma in the same manner as the aurora.