The Atacama Desert in Northern Chile, renowned for its arid conditions and exceptional stargazing opportunities, recently experienced an unusual snowstorm that led to the temporary shutdown of the Atacama Large Millimeter/submillimeter Array (ALMA) observatory. This rare weather event forced ALMA into an emergency “survival mode,” impacting its ability to collect vital astronomical data.
Impact of the Snowstorm on ALMA
ALMA, located on the Chajnantor plateau at an altitude of approximately 5,000 meters, is equipped with 66 high-precision antenna dishes that capture faint signals from space. The facility benefits from the Atacama’s unique atmospheric conditions, which significantly reduce interference. However, during late June and early July 2025, ALMA was struck by a localized snowstorm that required the repositioning of its dishes to prevent snow accumulation. This maneuver temporarily halted observations, although telescopes located a few hundred miles away, like the Southern Astrophysical Research (SOAR) Telescope and the Vera C. Rubin Observatory, remained unaffected.
The snow quickly melted due to the intense solar radiation characteristic of the Atacama, which is known for its minimal precipitation. In fact, it is estimated that the latest snowfall largely sublimated, a process whereby solid snow transitions directly into gas without becoming liquid, as reported by NASA Earth Observatory.
Changing Climate Patterns in the Atacama
The Atacama Desert, often cited as one of the driest places on Earth, has recorded significant changes in its climate patterns in recent years. Historically, it saw no rainfall from October 1903 to January 1918. Yet, instances of snowfall have occurred in 2011, 2013, and 2021, indicating a shift in the climate. Unseasonal rainfalls, including those from the previous year, have prompted vibrant blooms of desert flowers, showcasing the area’s underlying ecological resilience.
The implications of these climatic changes extend beyond aesthetic observations. In March 2015, an anomaly in weather patterns resulted in severe flooding in the coastal city of Chañaral, which borders the Atacama. The Salado River rose to a depth of approximately 4.5 meters, causing extensive damage to infrastructure and resulting in 31 fatalities. Such events underscore the potential impacts of anthropogenic climate change in a region unaccustomed to extreme weather.
As the Atacama’s climate continues to evolve, the scientific community may face new challenges. The occurrence of snow could become a regular obstacle for facilities like ALMA, necessitating adjustments to operational protocols and equipment. The ongoing research into the changing climate will be critical for understanding both local and global environmental trends.
The Atacama Desert remains a focal point for scientific exploration, and the recent snowstorm serves as a reminder of the delicate balance between advanced technology and the natural world. As researchers adapt to these new realities, the quest for knowledge about our universe continues amidst the changing conditions of one of Earth’s most unique landscapes.
