EARTHSHINE
2 FEBRUARY 1987
Bright Craters in Earthshine
by
David O. Darling
I went out tonight to observe the four day old crescent Moon and to study the Agarum Promontory region of the Moon. As the sky became darker 00:15 UT, I decided to pan the 12.5 f5 Newtonian telescope with a 25mm eyepiece into the earthshine. Upon looking I could see six features glowing blue in the darkness. The brightest was the crater Aristarchus, with Manilius and Menelaus being close together in brightness. The crater Copernicus and possibly Delambre were the last two. The final glowing formation was the ray from the crater Tycho that extends toward the crater Aristarchus. This was most apparent in the Mare Nubium region, located at Longitude 25 south by latitude 25 west. The ray of Tycho had the appearance of a glowing aurora streamer. I observed this activity for about 10 minutes and then closed down for the night.
UT Date: 2 February 1987.
Time of Observation: 00:15 UT
Name of Formations: Aristarchus, Manilius, Menelaus, Copernicus, Delambre, and Ray of Tycho.
Age of Moon: 4.82 days.
Altitude of Moon: 39 degrees.
Color & Variations: Sea blue, no variation detected, was constant.
Brightness of Phenomena: Approximately 5th to 6th magnitude.
Observer Location: Sun Prairie, Wisconsin, U.S.A. 53590, Latitude: 43.186 N. by Longitude 89.220 W.
Name of Observer: David O. Darling
Experience of Observers: Observing for 24 years, have been studying the Moon for L.T.P. for 8 years.
Seeing Conditions: Excellent
Transparency (Faintest Magnitude with eye): 4th magnitude, located in city do not have dark skies.
Telescope Used: 12.5 F5 Newtonian Cave Reflector with a 25mm eyepiece.
Rendition of the Moon showing its appearance the night of the event. Made using Reading Information Technology Inc. (RITI) Moon map program.
SOLAR TERRESTRIAL ACTIVITY REPORT
When examining the solar data I found a brief increase in the Planetary A index just prior to the event, and a slight increase in the Solar flux.
Conclusion: At the time of the observation I believed that I witness a lunar transient phenomena event. But after passage of 17 years, I've decided that it not a true event on the Moon but just the product of clear skies and excellent reflection from the Pacific Ocean. Depending where the Moon reside over during that time of the Lunation will determine how bright the Earthshine will be.