水星 月惑星研究会 関西支部 （最新）
Mercury Image 2002/06/29
Frank J Melillo
Frank J Melillo(Celestron 203mm Schmidt Starlight Xpress MX-5)
Dear all Mercury observers-
I don't realize until today that I had imaged Mercury the same part of the surface on July 15, 2001 and June 29, 2002. It has a similar elongation as in July 2001 and they both showing the same CM longitude at 268 degrees!
Here are two sets of images July 15, 2001 and June 29, 2002 to compare. All images are showing the same feature Solitudo Aphrodites in the northern hemisphere!
I am beginning to wonder and finally I get the picture. It seems that Mercury is always facing the same part of the surface toward the sun. But...
A century ago, G. V. Shaiaparelli, W. F. Denning, E.M. Antoniadi and few others assumed that Mercury rotated 88 days with the sun; just like our Moon does to the earth. They observed the same time each year when Mercury appeared in a favorable position. It showed the markings which appeared to be in the same place. They assumed one revolution around the sun equal to one rotation. That what we are seeing now.
[Frank J Melillo Holtsville NY U.S.A]