Light pollution, or artificial illumination projected into space, has the effect of making the sky itself glow and obscuring the stars. Astronomers have recognized for years that the condition is poor for observing the stars, yet it also has significant, detrimental effects on many organisms, including plants, animals, and even people. More than 80 percent of humanity is affected by light pollution, as it steals away our view of the skies. For thousands of years, animals have looked into the sky and seen it bustling with stars and stellar constellations. In many cities and densely populated areas around the world, however, this isn't the case. Light pollution is defined by Oxford Languages as the “brightening of the night sky caused by street lights and other man-made sources, which has a disruptive effect on natural cycles and inhibits the observation of stars and planets”.
Although we as humans contribute to light pollution, we are nonetheless negatively impacted by it. Throughout the world, the effects and consequences of light pollution are evident. According to National Geographic, over 80% of people in the world, and 99% of Americans and Europeans live under the sky glow every night. Sky glow is the brightening of the night sky from artificial light sources such as street lights and car lights, along with interior lighting from buildings. For astronomy, sky glow is devastating as it reduces the visibility of distant stars and stellar objects. Astronomers call it the “decrease of the signal-to-noise ratio”. According to the Florida Atlantic University, light pollution in the United States is seen to be growing at a constant rate of around 6% per year. It is such a significant issue that many new telescopes are being built in remote areas or in dark sky sites to avoid the skyglow from civilization and nearby cities. Dark sky sites are places around the world where you can experience the night sky at its fullest. Light pollution is restricted in these areas so it's an ideal place for people who want to go stargazing.
Additionally, this glow is harmful to humans and disrupts our circadian rhythm. Our circadian rhythm is our body's natural process of regulating the sleep and wake cycle. When it turns dark outside, our bodies naturally release melatonin, a hormone that induces sleep. With the introduction of a higher amount of nighttime light, our bodies lower the production of this hormone. This results in sleep deprivation, fatigue, headaches, stress, anxiety, and other health problems. Furthermore, a similar effect is given by blue light, which is emitted from the LEDs commonly found in our everyday phones and computers. Blue light itself has its role in the increase of skyglow. A collaborative study done between the Mental Health Unit, the Department of Public Health Solutions, and the National Institute for Health and Welfare (THL) in Helsinki, Finland, found that 2 hours of blue light (460 nm) during the evening suppresses melatonin production. The most suppression was achieved during exposure to the shortest wavelengths, such as violet light (424 nm). Along with this, a shocking discovery occurred that even the longest wavelengths like red (631 nm) suppressed melatonin production with your eyes closed at night. This means that if you're in a densely populated region with light flooding into your room while sleeping, it could still affect your circadian rhythm.
Streetlights are one of the biggest producers of light pollution globally. According to physicsworld, most of Europe is switching to LED street lighting in their towns and cities since it is much cheaper and more energy efficient. These lights would be on all night, causing yet another increase in the skyglow around major cities in Europe. Most of these street lights have bulbs that emit light in nearly 360 degrees. This light illuminates the streets, but at the same time, it is reflected into the sky. This amount of light at night is unnecessary for us to move around and creates skyglow. Finally, the most alarming problem of light pollution is its effect on animals and our ecosystems. Elke Langencucher, a student at the UNESCO world heritage conservation University College of Dublin, describes how light pollution affects habitats as a whole. Many animals are seen as not being able to use suitable habitats just because they are lit up or disrupted during their nocturnal cycle.
How can you help? The issue of light pollution can easily be prevented by anyone in their home and for people around them. The easiest way to help the cause of keeping our night sky unpolluted is as simple as turning off your lights before you go to sleep, avoiding driving at night, closing your drapes and blinds at night to keep light out of your bedroom, and using fewer lights when indoors. Furthermore, you can raise awareness of light pollution in your town or city.
Hopefully, you have learned about the cautions of light pollution and some ways that you can make an impact on our starry nights. Happy stargazing!
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