A bright, anorthosite-rich outcrop in southern Madagascar has drawn attention for its resemblance to the Moon’s surface. The feature, known as the Saririaky massif, was photographed from the International Space Station on August 28, 2026, and later highlighted by NASA’s Earth Observatory.

Anorthosite is a coarse-grained igneous rock composed primarily of plagioclase feldspar. It forms in large bodies when magma cools slowly beneath the surface. The Saririaky massif spans roughly 100 square kilometers and is embedded within a ductile shear zone where surrounding rocks have been deformed by tectonic forces. Linear patterns in the surrounding terrain indicate a history of high-pressure metamorphism linked to the assembly of the supercontinent Gondwana.

Scientists believe the massif originated during the late Precambrian, more than 600 million years ago, when fragments of what are now Africa, India, Madagascar, Australia, and Antarctica collided. In this tectonic context, a second anorthosite body approximately 60 kilometers to the north may have been stretched and pulled apart, forming a boudinage structure.

Anorthosite is also found on the Moon, where it makes up the bright lunar highlands. These lunar rocks are over 4 billion years old and were sampled during the Apollo missions. Because lunar samples are limited, researchers study Earth-based anorthosites as analogs. Notably, anorthosites in the Beartooth Mountains of Montana closely match the composition of their lunar counterparts.

The photographed massif was captured by an astronaut using a Nikon Z9 camera with a 400-millimeter lens. The image was taken during Expedition 75 and later enhanced to improve contrast and remove optical distortions. It was released by NASA’s ISS National Lab as part of its effort to make astronaut-captured Earth imagery publicly available.

Anorthosite formations in Madagascar have been documented in scientific literature since at least the late 20th century. A 1998 study by Ashwal et al. in *Contributions to Mineralogy and Petrology* detailed the petrology and geochemistry of Madagascar’s massif-type anorthosites. Additional research published in *Precambrian Research* in 2000 examined deformation patterns in the region, linking them to ancient tectonic activity.

NASA’s Earth & Solar System website noted in 2017 that impact processes have shaped the lunar highlands, reinforcing the relevance of studying terrestrial anorthosite analogs. Earlier, in 2020, the NASA Earth Observatory published a feature on Montana’s anorthosite deposits, underscoring their value in planetary science research.

While Madagascar’s anorthosite is not unique globally—similar formations exist in Canada, Scandinavia, and India—it remains a key site for understanding both Earth’s deep geological history and the evolution of planetary crusts. Its study continues to inform broader questions about the formation of rocky bodies in the solar system.