Mare Imbrium, morning here, evening there

Mare Imbrium, the Sea of Showers, as it appeared during Moon’s Last Quarter phase on the morning of August 5, 2026. The distinct crater with spidery ejecta lines radiating from it is Copernicus. With a diameter of about 711 miles, Imbrium is one of the largest craters in the Solar System. A colossal impact from a protoplanetary object during the Late Heavy Bombardment produced the huge ring nearly four billion years ago. Image Credit: Stella-Luna Observatory / James Guilford

Continuing to explore daytime imaging of Moon, August 5 presented us with good skies and a Last Quarter lunar phase. One of our favorite areas to observe is Mare Imbrium, filled with subtle detail and a mountainous arc, the Montes Apenninus defining much of its shape. Last Quarter occurs when the light on Moon’s Earth-facing side has proceeded half way from Full to New — in other words, it’s afternoon or late day at Imbrium. The setting Sun brightly illuminates the mountain tops of Iridium’s eastern edge, along with the eastern walls of craters within or nearby. A “bonus feature” is crater Copernicus, just south of Iridium‘s defining mountains, with its deep, textured walls, central peaks, and expansive ejecta rays. The Sea of Showers has much to offer viewers.

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