As humanity’s connection to the night sky fades, a term has emerged among astronomers to describe the sorrow associated with this loss: “noctalgia,” which translates to “sky grief.”
In addition to the environmental challenges we face, such as air and water pollution and climate change, we have created another form of pollution—light pollution. Most of the light pollution originates from ground-based sources. While humans have relied on campfires and handheld lanterns for centuries, the proliferation of electric lighting is staggering. We illuminate office buildings, streets, parking lots, and homes, often with excessive and inefficient lighting practices. The switch to energy-efficient LED lighting has, ironically, exacerbated the problem, as lights are left on continuously without consideration for the environmental and financial costs.
The darkest skies resembling those known to our ancestors can now only be found in the remotest deserts, wilderness areas, and oceans. The advent of satellite communication “constellations,” exemplified by SpaceX’s Starlink, has introduced a vast number of satellites into orbit, disrupting deep-space astronomical observations and increasing the overall brightness of the night sky. Some researchers estimate that even the darkest night skies, in the most remote regions, are now 10% brighter than they were half a century ago.
The loss of the night sky carries tangible and cultural consequences. It erases a repository of human cultural knowledge, as cultures worldwide have used the sky to weave stories and myths into constellations. Today, city dwellers are fortunate to see even the brightest stars, let alone familiar constellations. Millennia-old sky traditions are not mere tales but essential elements of cultures and societies. Shared constellations connect people across time and place, making this loss a part of our collective heritage.
Wildlife is also affected, as species with night-adapted senses struggle when the night sky becomes as bright as the day. Circadian rhythms are disrupted, leaving animals vulnerable to predators or unable to locate prey.
In response to the harm caused by light pollution, two astronomers have coined the term “noctalgia,” denoting collective sorrow over the diminishing access to the night sky. Efforts are underway to combat this issue, including the establishment of dark-sky reserves, where communities pledge to limit light pollution. However, such reserves are often located in remote areas. Collaborative efforts with community and business leaders to adopt night-friendly lighting practices are also gaining traction.
Addressing satellite-based pollution requires international cooperation and pressure on companies like SpaceX to adopt responsible practices. With concerted efforts, it is hoped that one day, noctalgia will become a thing of the past.