Our ancestors were stargazers; they would carpe noctem. In their times, they would look above at night and witness a starry landscape reaching for the horizons, all engulfed by our cloudy Milky Way galaxy. Thousands and thousands of stars, perhaps millions of light years away, strolling in the void. They would feel themselves lifting up into the night sky and would clutch the grass beneath them to stay rooted. Those people didn’t just see the sky; they saw what lied beyond. Such beauty, and that too in darkness, would have, no doubt, filled them with awe.
Today, more than 80% of human population cannot witness that marvel. Today, according to the Atlas of Night Sky Brightness, 83% of night skies are at least 10% brighter than their natural level. Today, all we see, when we tilt up our heads, is a hazy glow encumbering the cityscape, the reason being light pollution.
Sky glow as a result of extreme misdirection of light on a large scale
Light pollution isn’t like our everyday carbon emissions or chemical waste but actually it’s excessive and misdirected light which is produced as a result of human activities. It’s been there since the dawn of electricity, when Thomas Edison invented the light bulb; but it’s not as if I am a light fascist or anything. The light bulb was revolutionary; I mean it lit up the world. But the problem is too much light and it’s starting to show its consequences.
Too much light affects eventually everyone, from flora to fauna. It has hampered astronomers to clearly see the sky, destroyed ecosystems and disrupted many natural processes, even though we may not notice it. For example, baby sea turtles are born on land and if they don’t immediately find their way to the sea they’ll die of hunger and thirst. They do this by following the glimmer of light on the sea’s surface but now, light emerging from the city is so intense that they mistake it for the sea and go there instead, sometimes dying from car accidents shortly later.
Zooplankton, like Daphnia, shelter from predators in deep dark waters at daytime and come above to feed on the algae at night. But increasing light pollution makes them think that night has not fallen even after it actually has, which eventually results in their starvation, disrupting the entire marine food chain as they are at the bottom of it and algal bloom on the water surface hampering marine life beneath.
Birds are also attracted towards light sources from the city and hence crash into structures, unknowingly, at night. Migrating birds too are misguided and meet similar fates. Almost 9.8 million to 1 billion birds die every year by such accidents which our activities brings about.
Many other species rely on light for reasons like breeding times but today they are a victim of our creations. Surely all of this is inhumane and can spark the passion in us to do something about light pollution.
Moreover, today most of us have sleep disorders. One big reason is light at night. Our suprachiasmatic nucleus regulates the secretion of the sleep hormone, melatonin, and sits right above our optical nerve, always scanning for light. At night when it is dark, the production of melatonin pumps up to give us a good night’s sleep but that is proving to be quite hard today when even if our room is dark the city’s lights peep in. It’s as if the 24-hour sleep cycle of humans is not balanced anymore which can lead to stress issues too. Also recent study shows that excessive light can increase risk of cancers like breast cancers or those that require spreading of hormones. That is exactly why the International Agency for Research on Cancer dubbed "night work" as a carcinogen, in 2007.
Not only that, but lighting is also responsible for one-fourth of global electricity consumption which is 5250 TWh! As you’ve might have figured out, a lot of fossil fuels go into the process to bring about that much electricity. Even if we contribute a little on our side, for example by turning the lights off before leaving a room, we can, in the big picture, save a lot of greenhouse emissions and money. In 2007, Terna, the company that manages the electricity flow in Italy, reported a massive saving of 645.2 million kWh in electricity consumption during the daylight saving period from April to October. It attributes this saving to the delayed need for artificial lighting during the evenings. To make things worse, the modern incandescent bulbs are blue, which is the wavelength scattered furthest; that would increase the range of the sky glow around the city. Although we cannot stop using these bulbs because they offer really high efficiency, but until other types of bulbs are invented like the non-harmful sodium bulbs, we need to use cutoff fixtures on light bulbs to restrict light rays only to where required.
Left: - Light polluted night sky. Right: - The same sky without light pollution. This is what we are missing. Most of us think that the stars are not visible from Earth. They have absolutely no idea of what lies above. Courtesy of the International Dark Sky Association
In 1994, in Los Angeles, the people of the city freaked out after seeing the Milky Way galaxy for the first time in the sky, in an electricity blackout, mistaking it for an alien thing. Neil deGrasse Tyson says, "When you look at the night sky, you realize how small we are within the cosmos. It's kind of resetting of your ego. To deny yourself of that state of mind, either willingly or unwittingly, is to not live to the full extent of what it is to be human." Initiatives like the Earth Hour can make the people fully realize what their actions are resulting in. We must do whatever is required, because the people who knew the beauty of the night sky are dying. If we don’t preserve their memories, no one would ever know what liveliness lies above their heads.