NASA's Earth Observatory featured an astronaut photograph of the Saririaky anorthosite massif in arid southern Madagascar, taken from the International Space Station on August 28, 2026. The image was published as the Image of the Day for October 5, 2026.

Anorthosite, an intrusive igneous rock made of large mineral crystals, forms the light-colored lunar highlands visible from Earth. The Saririaky outcrop covers about 100 square kilometers (40 square miles). Scientists think the massif formed in the late Precambrian, at least 600 million years ago.

The surrounding rocks sit within a ductile shear zone, where high pressures and temperatures metamorphosed and reshaped the rock into north-south-trending patterns. Geologists think this deformation occurred as pieces of what are now Africa, India, Madagascar, Australia and Antarctica collided to form the supercontinent Gondwana. Some scientists have suggested that another massif about 60 kilometers (40 miles) north was pulled apart from Saririaky in the process, creating a large-scale boudinage structure. Because lunar samples from Apollo missions are limited, researchers also study comparable terrestrial rocks, such as anorthosites in Montana's Beartooth Mountains.