NASA Astronaut Photo Reveals Monterrey, Mexico, Surrounded by Sierra Madre Ridges

Curving mountain ridges of the Sierra Madre Oriental surround Monterrey, Mexico, creating one of northeastern Mexico’s most striking landscapes. Astronauts aboard the International Space Station photographed the city and its folded limestone mountains on August 26, 2026.

Monterrey’s urban landscape and population

Monterrey, the capital of Nuevo León, is one of Mexico’s most important industrial centers. The metropolitan area supports major industries, including iron and steel production, manufacturing, textiles, processed foods, glass, and plastics. According to the 2020 census, approximately 5.3 million people live in the metropolitan region.

Although Monterrey’s overall population has grown, fewer people now live within 5 kilometers (3 miles) of the city center than in 1990. Researchers have identified similar patterns of outward urban expansion in several Mexican metropolitan areas.

How the Sierra Madre mountains formed

Monterrey’s growth is shaped by the rugged terrain along the southern edge of the city. The region contains thick layers of limestone that were deposited during the late Mesozoic Era. Between roughly 80 million and 50 million years ago, geological forces folded these layers and helped form the eastern Sierra Madre mountain ranges.

Over millions of years, erosion removed weaker layers of rock and exposed the harder limestone beneath. This process created the parallel ridges and distinctive folded formations visible in the astronaut photograph.

The Santa Catarina River and Monterrey’s environment

The Santa Catarina River cuts through the mountains before reaching the semi-arid floodplain where Monterrey is located. The river contains little water during much of the year, but its channel plays an important role in carrying runoff during seasonal summer storms.

The river corridor also provides valuable habitat for plants and wildlife within the heavily developed metropolitan area. Its natural drainage system is especially important because intense rainfall can produce sudden flooding in the region.

Sierra de las Mitras and Cerro de la Silla

The Santa Catarina River flows between Monterrey’s urban center and several prominent mountain formations. One of the most recognizable is the Sierra de las Mitras, a protected natural area that rises approximately 1,500 meters (4,900 feet) above the city.

Elevation creates noticeable changes in the landscape. Cacti and thorny shrubs grow on the warmer, drier lower slopes, while cooler and wetter conditions at higher elevations support oak and pine forests. Nearby Cerro de la Silla, also known as Saddle Hill, is another iconic landmark that stands in sharp contrast to Monterrey’s urban development.

NASA Space Apps Challenge in Monterrey

Near Monterrey’s border with the Sierra Madre Oriental is the University of Monterrey, which hosts the NASA Space Apps Challenge. The annual hackathon will take place in person and virtually in November 2026 at locations around the world.

Participants will use NASA and partner-agency data to develop solutions related to software, astrophysics, space exploration, agriculture, and other scientific fields.

About the astronaut photograph

NASA astronaut photograph ISS075-E-70481 was taken on August 26, 2026, using a Nikon Z9 digital camera with a 400-millimeter focal length. The image was acquired by a member of Expedition 75 aboard the International Space Station and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit at NASA’s Johnson Space Center.

The photograph was cropped and enhanced to improve contrast, and lens artifacts were removed. The International Space Station program and the ISS National Laboratory support the collection and distribution of astronaut photographs of Earth for scientific research and public education. More images are available through NASA’s Gateway to Astronaut Photography of Earth. Story by Lindsay Dorman.