Another ray
On the evening of April 20, 2021, the Moon achieved First Quarter. While it was too early to see the Hesiodus ray, I decided to check in on southern Mare Nubium with my 3-inch Tele Vue refractor. I was not disappointed.
While Hesiodus was completely immersed in shade, Pitatus hugged the terminator, offering an eye-catching interplay of light and shadow. It wasn’t long before the view baffled me: Beaming across its flat floor was a narrow ray that broadened slightly toward the crater’s sunlit central peak — splitting the long shadow of Pitatus’s eastern wall in two.
While this ray was a poor cousin to the Hesiodus ray, it warrants attention. Perhaps it is created from some topographical depression in or near the crater Pitatus G, a smaller crater on the rim of Pitatus. The image above was taken through my 3-inch scope, and it does not do the clarity of the feature justice. It looked at first like an illuminated walkway reaching from Pitatus G to the shining monolith that is Pitatus’ central peak. I then noticed lunar ray material north and south of the peak also spreading out across the floor like wings, giving it a birdlike quality.
At the time of my observation, the Moon was 57 percent illuminated and 8.1 days old. The Sun’s colongitude was 14°, meaning the selenographic (lunar) longitude of the morning terminator was –14°. This month, a similar, but not exact, circumstance occurs March 11 at 14:30 UT, when the Moon will be 61.2 percent illuminated and 8.4 days old, with a colongitude of 14°. Will the sunrise ray in Pitatus reappear?
By the way, the sunrise ray in Hesiodus may occur about seven hours and 15 minutes later. As always, send your observations to sjomeara31@gmail.com.