Although the moon has been observed by amateurs and professionals for many centuries, a phenomenon which is considered extremely rare is that of a lunar ray. More specifically, when the rising or setting sun is at a very low angle relative to a lunar feature such as a crater, even a couple of degrees, sunlight may pierce through one of the clefts in the crater's wall and project a ray across the crater floor. Although observational reports of such rays date back to the mid-1800's, there exist but a few such reports and even fewer images. This project is something I started to pursue during the spring of 2003 after reading the excellent article by Robert Robinson in the Reflector (Dec/2002, pg 15). To date, reports indicate that these rays may be observed for only a handful of craters and only during a two- to three-hour window. For further details, the interested reader is directed to Rob Robertson's web site or Jeff Medkeff's web site where such observation opportunities and further details may be obtained.

With respect to the projected viewing opportunities, I have produced a complete chronological series (for all lunations in 2003-2004) using Harry Jamieson's DOS-based LUNAR TOOLKIT software for the light ray targets defined by Roberton. Since these predictions are driven by the solar illuminating angle, I decided to use an angle of +2°.