Sinus Iridum

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Sinus Iridum, or the Bay of Rainbows, is a large, flat lava plain on the Moon. It forms a northwestern extension of Mare Imbrium and is bordered by the Montes Jura mountains. The southwest edge is Promontorium Heraclides and the northeast edge is Promontorium Laplace. The bay was created when the floor of a huge impact crater was flooded with basalt lava, leaving a smooth, level surface with some wrinkle ridges. It has a few small craters along its edge, such as Heraclides E, Laplace A, and Bianchini G.

Its center is at 45.01° N, 31.67° W, and its diameter is about 249 kilometers. Sinus Iridum is one of the largest Late Imbrian-age features. It was the planned landing site for China’s Chang’e 3 mission, which landed nearby in Mare Imbrium. When the Moon is a few days past new, Montes Jura can be seen along the terminator, creating a curved shape often called the Golden Handle. On lunar maps, craters near Promontorium Laplace are labeled with letters on the side closest to Promontorium Heraclides.