Moonrise over Maunakea

In this photo the full Moon can be seen rising over Maunakea. The dormant volcano is home to the Gemini North telescope, one half of the International Gemini Observatory, supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab, and also a number of other observatories. The dark form below the Moon is the shadow of Maunakea. Because of an optical effect,  the shadow appears triangular, even though Maunakea itself is not. The shadow of the volcano is simply so long that any irregularities blur into a rectangle, which tapers off into the distance before appearing to converge at a single point on the horizon, an effect caused by both the curvature of the Earth and the geometric perspective.

While the summit of Maunakea is very dry, the island of Hawai‘i is tropical and often cloudy because of the high humidity. The difference in altitude from the Pacific Ocean to the top of the Maunakea — about 4000 meters (14,000 feet) — creates an inversion layer in the atmosphere. Trapped, the thick clouds often obscure the landscape and seascape below, creating an unusual but amazing view from the mountaintop.