A photograph taken by an astronaut aboard the International Space Station on August 26, 2026, shows the winding ridges of the Sierra Madre Oriental extending around Monterrey in northeastern Mexico. The capital of Nuevo León state and Mexico’s second-largest metropolitan area, Monterrey is home to industries ranging from iron and steel to textiles, processed food, glass, and plastics manufacturing. According to the 2020 census, 5.3 million people live in the metropolitan area. While the city’s total population has grown since 1990, the number of people living within 5 kilometers of the center has declined.
Urban expansion is constrained by mountains formed from limestone layers created during the Late Mesozoic and folded approximately 80-50 million years ago. The erosion of weaker rocks formed the prominent ridges seen today. The Río Santa Catarina passes through the mountains and reaches the semiarid floodplain; although it usually carries little water, it collects runoff from summer rainfall and provides natural habitat for wildlife within the city.
Designated a state nature reserve in 2000, Sierra Las Mitras rises approximately 1,500 meters above the city. As elevation increases, the landscape transitions from cacti and thorny shrubs to oak and pine forests. Cerro de la Silla is another prominent formation. The photograph was taken by one of the Expedition 75 crew members with a Nikon Z9 camera, under NASA’s ISS075-E-70481 record. Monterrey University will host the NASA Space Apps Challenge event in November 2026.
Why it matters
The image shows that, as Monterrey’s population and industry grow, the city is also developing in an area physically surrounded by mountains and a semi-arid floodplain. While the population around the center is declining, the expansion of the metropolitan area raises questions about how urban density and development are distributed. The fact that the Río Santa Catarina collects surface runoff during rainy periods points to an element that needs to be monitored not only in terms of natural areas within the city but also for flood risk management. The elevation-related change in vegetation on Sierra Las Mitras and the area’s status as a nature reserve make the relationship between expansion and ecological areas visible to city residents, local governments, and environmental researchers. The fact that the NASA Space Apps Challenge will be held in Monterrey also provides a context that increases the scientific and public interest in this geography.