Light Pollution: Stealing The Stars From Our Eyes

Light pollution is a growing problem that has obscured the night sky for many people around the world. Electric lights have undoubtedly revolutionised our lives, but the excessive use of artificial light has led to various issues. Light pollution not only hampers our view of the stars, planets, and galaxies but also has harmful effects on wildlife, ecosystems, energy consumption, and human health.

The bright lights from cities and excessive illumination have made it difficult for people, especially those living in urban areas, to see the stars clearly. In big cities, it has become a challenge to even catch a glimpse of prominent constellations like the Big Dipper. Research suggests that due to light pollution, one-third of humanity, including 60% of Europeans and 80% of Americans, can no longer see the Milky Way.

Light pollution is caused by various sources such as streetlights, buildings, billboards, neon signs, car headlights, and satellites. The excessive brightness and stray light falling where it is not needed contribute to the problem. This artificial lighting affects wildlife, with documented impacts on sea turtles, birds, bats, corals, and other species. Additionally, it disrupts human health by altering our biochemical rhythms and sleep patterns.

Despite the challenges, there is growing awareness and efforts to combat light pollution. Organisations like DarkSky International and the International Dark-Sky Association are working to reduce light pollution through education, advocacy, and the establishment of responsible lighting codes. Some cities are also taking initiatives, such as using more energy-efficient lights and reducing non-essential lighting, to mitigate light pollution and restore the night sky.

Light pollution is the effect of artificial lights on the night sky

The night sky has long been a source of wonder and inspiration for humans, with our ancestors weaving stories into the star-studded tapestry above. However, due to light pollution, the night sky is now largely inaccessible to those living in urban areas. Light pollution creates a permanent "skyglow" that drowns out the natural darkness, making it difficult to see stars, planets, and galaxies. This issue is particularly prevalent in big cities, where it is common to only glimpse a handful of the brightest stars. In fact, it is estimated that one-third of humanity, including 60% of Europeans and 80% of Americans, can no longer see the Milky Way due to light pollution.

The primary source of light pollution is artificial lighting from cities, which includes streetlights, building lights, billboards, and car headlights. These lights are often not properly shielded, causing them to shine light in all directions, including upwards into the sky. Additionally, the recent increase in the use of bright LEDs has contributed to the brightness of the night sky. The excessive brightness and glare from these lights not only affect our view of the night sky but also have harmful consequences for both wildlife and humans.

For wildlife, light pollution can disrupt the life cycles and behaviors of various species. For example, sea turtles need dark beaches for nesting and are negatively impacted by bright lights. Migrating birds can become confused by bright city lights, causing them to fly in circles until they drop from exhaustion or crash into buildings. Light pollution has also been linked to issues in other species, including bats, insects, plants, fish, marine invertebrates, and primates.

Human health is also affected by light pollution. Exposure to certain wavelengths of light, particularly blue light, at night can disrupt our sleep by suppressing the production of melatonin. Additionally, the alteration of natural light levels can impact our biochemical rhythms, potentially affecting our health in various ways.

To combat light pollution, several measures can be implemented. These include shining lights downwards towards the ground instead of up into the sky, using lower brightness levels, shielding lights to direct them only where needed, and using timers or motion sensors to turn lights off when not in use. By implementing these solutions, we can reduce light pollution, preserve the beauty of the night sky, and mitigate the negative impacts on wildlife and human health.

Light pollution is getting worse

The stars are vanishing before our eyes, as increasing levels of light pollution mean that fewer stars are visible in the night sky. A global community science project found that the night sky is becoming around 10% brighter each year on average. While this may seem trivial, it is affecting the lives of many different animals, as well as being an expensive waste of power.

Dr Christopher Kyba, the lead author of a study reporting the results of the project, says:

> The rate at which stars are becoming invisible to people in urban environments is dramatic. If the brightening of the night sky continues at the current rate, a child born in a place where 250 stars are visible will only be able to see 100 stars there on their 18th birthday.

The issue of light pollution was first recognised in the 1970s, when astronomers began to see the impact of the rapid increase in artificial light on their work. At this time, the sky is estimated to have been becoming brighter by between three and six per cent every year. However, as artificial lighting has continued to be rolled out, the rate has increased.

Using over 50,000 observations made between 2011 and 2022, researchers suggest that the night sky is getting lighter by an average of 9.6% globally each year. Over an 18-year period, this would see the night sky get brighter by a factor of four.

The rate of increase is not constant throughout the world. In Europe, light pollution is increasing at a rate below the global average, at around 6.5% every year, whereas the same figure in North America is 10.4%. While there were not enough observations from the rest of the world to break down the increase by continent, the night sky is thought to be increasing in brightness by almost 8% every year.

These increases mean that around 30% of people worldwide can no longer see our galaxy, the Milky Way, which rises to 80% of people in North America.

However, it's not only the amount of light that's changing but also the colour. As LEDs become increasingly common, light pollution is becoming more blue in colour. While these lights are more efficient than older forms of lighting, they are also making it more difficult to monitor light pollution. Satellites aren't as good at spotting blue light, which could explain why a recent satellite-based study found that lit-up areas of the world were becoming brighter by only 2.2% every year.

Light pollution affects human health

Light pollution has various adverse effects on human health. Firstly, it can disrupt the natural circadian rhythm, or sleep-wake pattern, of individuals. This disruption is caused by the suppression of melatonin production, which is needed to keep us healthy. Melatonin has antioxidant properties, induces sleep, boosts the immune system, lowers cholesterol, and helps the functioning of the thyroid, pancreas, ovaries, testes, and adrenal glands.

Secondly, light pollution can lead to sleep disorders, such as shift-work sleep disorder and delayed sleep-phase syndrome. These disorders can have negative consequences for work, school, or social engagements.

Thirdly, light pollution has been linked to an increased risk of obesity, depression, diabetes, and breast cancer. For example, a study in Israel found a correlation between outdoor artificial light at night and breast cancer, with women in brightly lit areas having a 73% higher risk of developing the disease.

Lastly, light pollution can cause glare, which reduces contrast and limits our ability to see potential dangers at night, especially for aging eyes.

Overall, light pollution has far-reaching consequences for human health, and it is important to address this issue to mitigate these negative impacts.

Light pollution has consequences for wildlife

Nocturnal animals are particularly affected, as light pollution alters their environment, turning night into day. Predators use light to hunt, and prey use darkness as cover. Research scientist Christopher Kyba notes that "near cities, cloudy skies are now hundreds or even thousands of times brighter than they were 200 years ago. We are only beginning to learn what a drastic effect this has had on nocturnal ecology."

One example of the impact of light pollution on wildlife is the effect on sea turtles. Sea turtles hatch on beaches at night and find the sea by detecting the bright horizon over the ocean. However, artificial lights disorientate them, drawing them away from the ocean and towards danger. In Florida alone, millions of hatchlings die this way every year.

Light pollution also impacts migratory birds, which navigate by moonlight and starlight. Artificial light causes them to wander off course and towards cities, where they collide with illuminated buildings and towers. It can also cause them to migrate too early or too late, causing them to miss ideal conditions for nesting and foraging.

Additionally, insects, such as moths and butterflies, are drawn to bright lights, which can deplete their energy reserves and expose them to predators. This decline in insect populations can have a knock-on effect on other species that rely on insects for food or pollination.

Light pollution has far-reaching consequences for wildlife, disrupting natural behaviours and ecosystems. It is important to address this issue to protect the delicate balance of the natural world.

Light pollution can be reduced by using intelligent lighting

Light pollution is the excessive or misdirected artificial light produced by human-made sources such as streetlights, billboards, and buildings. It has been estimated that 80% of the world's population lives under light-polluted skies, with 99% of the U.S. and European populations affected. Light pollution has harmful effects on wildlife and human health, and it diminishes our sense of the universe.

Artificial lighting in outdoor spaces is deemed necessary for people to feel secure and comfortable when navigating in the dark. While it may be impossible to eliminate light pollution, it can be significantly reduced through the use of intelligent lighting. Intelligent lighting controls, such as the DALI systems offered by zencontrol, are equipped with smart technology and connectivity, providing a range of capabilities for dark sky preservation. These systems can be programmed to adjust lighting levels based on ambient light conditions, astronomical time, or specific events. They can also be integrated with sensors, weather data, and astronomical databases to automatically optimize lighting settings for minimal light pollution.

• Dimming and scheduling: Lighting control systems with dimming capabilities allow for the adjustment of artificial light intensity. Schedules can be employed to automatically turn off or dim lights during specific periods, reducing unnecessary light emissions.
• Motion sensors: Motion sensors detect the presence or movement of people and animals, triggering lights to turn on only when necessary. This technology helps prevent over-illumination in outdoor spaces by ensuring that lights are activated only when needed, reducing energy waste and minimizing light pollution during idle times.
• Integration with sensors and data: Intelligent lighting systems can be integrated with sensors, weather data, and astronomical databases to optimize lighting settings. For example, lights can be dimmed or turned off during cloudy or rainy weather when natural light levels are lower.
• Adjustable color temperature: Intelligent lighting controls, such as the DALI system, allow for the adjustment of color temperature. By reducing the amount of blue light, which is responsible for brightening the night sky, the detrimental effects of artificial lighting on the visibility of stars can be minimized.
• Light zoning and regulations: Local authorities can introduce lighting zoning regulations to control the amount, intensity, and direction of artificial lighting in specific areas. Communities can ensure that outdoor lighting installations adhere to dark sky principles by enforcing regulations that include restrictions on fixtures, required shielding, and limitations on light levels.

By employing intelligent lighting technologies, significant reductions in light pollution can be achieved, preserving dark skies for future generations to enjoy. These efforts contribute to the protection of biodiversity, the promotion of human well-being, and the restoration of our connection to the universe.

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