Voiced by Sir Patrick Stewart in an episode of the National Geographic’s series “Cosmos”, astronomer William Herschel explained to his son that stars are merely “ghosts” in the sky, as they are so far away from the Earth that, by the time their light reaches us, they are already gone. His words went through my mind on one warm August night, while I was standing at the top of the Petrovaradin fortress in Novi Sad, Serbia, and trying to catch a glimpse of a meteor shower. The idea was to find a dark spot with a clear view of the night sky, but the task proved to be much more challenging than I had imagined. It was alarming to see the stars drowned out by the glare coming from the streets, the bridge, and the nearby shopping centre. The stars are undoubtedly gone, and their ghosts are having a hard time getting through.
By Ana Marković
What is light pollution?
According to the International Dark-Sky Association (IDA), light pollution refers to “inappropriate or excessive use of artificial light.” It can manifest differently, taking the form of a skyglow, which makes the night sky over metropolitan areas extremely bright; light trespass, or light illuminating places that don’t need it; clutter, which involves groups of light sources that are too bright and create confusion; and finally glare, that stands for excessive brightness that puts a strain on our eyes. Apart from preventing a clear view of the night sky, light pollution can cause damage to wildlife and ecosystems as well as to human health and safety.
A major part of outdoor lighting comes from street lights, billboards, illuminated properties, and private homes. This light fails to reach its target and it ends up being wasted on the night sky rather than staying focused on actual objects that need illumination. Wasted light also means excessive energy consumption and higher energy bills.
A global issue
Light pollution isn’t only evident in Serbia, but it creates problems globally. According to a study conducted in 2016, 99 percent of the continental United States and Europe is affected by some amount of light pollution. Also, observations from the Suomi NPP satellite suggest that a third of humankind is unable to see the Milky Way.
Countries that feature dense population face the highest amounts of light pollution. These include San Marino, Singapore, and Kuwait, among others, and their inhabitants are unable to see 99.5 percent of all visible stars without the help of some optical instrument. On the other hand, rural areas such as Central African Republic, Chad, and Madagascar are among those that experience the lowest degree of light pollution, and their inhabitants have a clear view of the Milky Way when they look up at the night sky.
A threat to wildlife
The Earth’s cycle of day and night regulates behavior of plants and animals, such as sleep, reproduction, and protection from predators. The over-illuminated night skies interfere with these processes and disrupt the life-cycle of many species, including mammals, birds, and amphibians.
Nocturnal animals spend the day sleeping and the night searching for food, so artificial light dramatically impacts their activities at night. While predators hunt with the help of the light, their prey relies on darkness to protect them, so excessively bright sky at night changes the rules of the game and affects the nocturnal environment in unexpected ways. Artificial glow has a negative effect on inhabitants of wetlands, such as frogs and toads, as their croaking time at night is a part of the breeding ritual. Light pollution interferes with this activity and consequently affects reproduction and population of these species.
Sea turtles are among those most gravely affected by light pollution. Although they live in the ocean, sea turtles hatch their eggs on the beach during night time. Hatchlings use the light from the horizon to orientate and find the way to the ocean, but artificial light can lead them in the wrong direction, which has deadly consequences.
Light pollution doesn’t only wreak havoc on the ground, but in the air as well, as it tampers with birds’ flight patterns and migration schedules. Birds that are night hunters orientate with the help of stars and moonlight, and artificial light can send them astray—towards buildings, for example—and cause collision. Furthermore, birds migrate according to seasonal schedule, so proper timing is essential. Light pollution can disrupt this routine and cause them to miss the right time for migration, which means missing out on optimal climate conditions for nesting or searching for food.
Artificial light that illuminates more than its intended target area results in wasted energy and higher bills. IDA estimates that wasted outdoor lighting costs the U.S. up to 3.3 billion dollars and increases the release of carbon dioxide at the rate of 21 million tons per year. A simple act of replacing old bulbs and fixtures with energy-saving alternatives could reduce these numbers significantly.
To cut down on energy bills, some homeowners have switched from standard incandescent bulbs to light-emitting diodes, or LEDs, which resulted in lesser energy consumption. LEDs and other energy-saving alternatives like compact fluorescents sparked a revolution that had a significant impact not only on individual households, but on cities as a whole as well. Upon replacing over 150,000 streetlights with LEDs, Los Angeles saved approximately 8 million dollars annually on energy costs.
Although LEDs may be the cheaper solution, if not used properly, the night sky will pay a much higher price. White LEDs that are commonly found in street lights emit a blue light that gets scattered across the sky and can potentially increase its brightness. Also, as people have a tendency to use LEDs more than necessary and illuminate larger portions of the area than actually needed, the light ends up being spread around and wasted. Dimmer, warm-white, and shielded LEDs reduce the costs and also help the night sky stay dark. You can learn more about different types of LEDs and their color temperature from IDA’s LED Practical Guide.
Tips on reducing excessive brightness:
- Use warm-white, shielded LEDs and compact fluorescents.
- Use outdoor lighting fixtures that are fully shielded and prevent light from falling on places where it isn’t needed.
- Remember to turn off the lights at night and after leaving an empty room.
- Use dimmers and motion sensors on outdoor lighting, if possible.
- Turn off electronic devices before you go to bed.
- If you live in a high-rise building, use drapes to minimize the chances of a bird collision.
Light doesn’t always lead to safety
Despite the persistent belief that bright lights at night reduce the crime rate and keep us safer, there is no scientific evidence that supports this claim. Numerous studies conducted in recent years have shown that street lights don’t play a part in preventing crimes. In fact, outdoor lighting may cause the opposite effect. In 2012, American Medical Association published a report that stated that “Glare from nighttime lighting can create hazards ranging from discomfort to frank visual disability.” Instead of increasing visibility, unshielded street lights produce a glare that goes directly into our eyes and tampers with our ability to see clearly. The brightness can make us feel blinded and we may need to put in more effort to adjust to low-light environments.
While there are initiatives in Serbia and worldwide with the aim to fight light pollution, it remains an issue that is often overlooked due to more urgent matters. It’s important to continue to educate people on the negative effect of too much brightness and what they can do to reduce energy consumption and preserve the darkness of the night sky.