Light pollution — why I cannot see as many stars in my night sky?
SpaceNuggets #10: Inspired by a guest lecture, diving into one of the lesser-known types of pollution and the importance of saving our night skies
Hi everyone, welcome to the overall 10th edition of the fortnightly series of Space Nuggets! Space Nuggets are bite-sized pieces on the latest astronomy events and the phenomenon behind them, intending to share the marvels of the world around us and the Universe with one and all!
In this article, we will dive into one of the most important issues plaguing humankind’s astronomy-related research efforts — light pollution!
At the beginning of February this year, I had the chance to attend a guest lecture at Jawaharlal Nehru Planetarium, Bengaluru by Dorje Angchuk from the Indian Astronomical Observatory, Leh-Ladakh on the Himalayan night skies as seen from Ladakh. His talk was mesmerizing, to say the least, every slide in his presentation was a picture he clicked as a part of his hobby of astrophotography, diving into anecdotes behind each of the pictures and the technicalities of their composition. But one of the themes that stood out throughout his talk was “light pollution” and how he has seen it change over Ladakh in his years as an astrophotographer. Today, I want to talk about just that, one of the often ignored and lesser-talked-about forms of pollution caused by humans.
What is light pollution?
The light bulb is a beautiful and amazing invention, right? It brought “light” to our lives in the dark, and is one of the most important inventions of humankind and today we cannot imagine our lives without them. But what happens when this same artificial light is used excessively, or inappropriately at night? It causes light pollution and it is a glaring issue in most major cities of the world.
Why is light pollution bad?
Before we even think about light pollution and astronomy, excessive lighting at night is harmful for us as human beings too. Firstly, it disrupts our sleep cycle, with the body not understanding when it is daytime and when it is night to wind down and sleep and also confuses animals and migratory birds. Moreover, we waste so much energy in these outdoor lights, which are often generated from limited fossil fuels. And yes, we are losing the opportunity to just look up and enjoy the view of the beautiful night sky above us and the cosmos.
According to an article by National Geographic, more than 80% of the world’s population and about 99% of Americans and Europeans live under a sky glow — a form of light pollution and can barely see more than a handful of stars at night.
How does light pollution affect astronomical research?
The unaided human eye can see celestial objects of apparent magnitude up to +6.0 (read more about apparent magnitude in my previous article) under dark skies, but with light pollution, the relative brightness of an object from Earth in the night sky dims down to as much as +3.0. As put by (as put by Florida Atlantic University,
Due to light pollution, we actually cannot see so many objects like nebulae, planets and stars or the Milky Way itself — which are available to us for free, by birthright.
Light pollution hinders astronomical research by making it difficult for telescopes on Earth to observe the night sky and study the celestial events — the other alternative is to send satellites and telescopes to the Earth’s orbit to study these events — but that’s going to be much expensive right?
Our dark skies are our natural resources, bestowed to us by the Earth for free, just like air, forests, and fossil fuels. But just like we are losing the other resources, we are losing out on clear empty spaces to observe the night sky and the wonders of the Universe very quickly.
What can we do to reduce light pollution?
The world has recognized this depleting resource of night skies and associations around the world have started creating “Dark Sky Reserves” — places where light pollution is very closely monitored and minimized with the help of local communities, so that night sky watching becomes easier and more enjoyable. These areas are usually located near observatories so they promote astronomy and become a good point of attraction for astro-tourism. At the same time, they also promote the rich cultural heritage of the local stories and historical events built around the starry nights. Since each human community has their version of how its ancestors interpreted the stars and planets and their movements, the “dark sky reserves” are a chance for us to look into the past with these stories and the future with our in-ground telescope observatories!
The first “dark sky reserve” in India was started by Dorje Angchuk in Hanle (in Ladakh) and it is a public reserve, which means anyone can visit it all year round!
But this is not all, we all can do our little individual bits too to reduce light pollution. We can make sure we use outdoor lightning only when we need it, keeping in mind that these direct the light down instead of up into the sky (this is one of the common causes of light pollution). We can also use cooler shades of light so as to cause lesser light pollution and lesser disruption for us, the wildlife and the environment.
I want you all to think about your early childhood memory of space, astronomy, and the night sky — was it observing some stars, or some constellation and listening to the stories around them? (Mine surely was, and I have been hooked on to them since then!). Think about how our future generations would miss out on experiencing this if they did not have dark skies to look up to.
Our night skies are one of our strongest and one of the few common threads with our past and our ancestors — connecting us to them through the powerful stories they weaved of the land and the sky. The skies are “our lab, observed through telescopes on Earth and space” — as mentioned by Dorje Angchuk in his talk— making it possible for us to observe events and proofs of all the theories we have been coming up with that simply cannot be seen on Earth, thus being one of the easiest ways to fuel astronomical research pursuits. They make us wonder in awe of what lies beyond and of our place in the Universe, and they kindle our curiosity to learn something more about things we can see — and those we cannot.
That’s all for this edition of Space Nuggets! Stay tuned for the next one a fortnight later, and till then, remember that we all have a little cosmic dust inside us, so you are nothing short of stellar yourself! Happy skywatching 🔭
Do you have any suggestions for questions, phenomena, and topics you would like to see in the Space Nuggets? Reach out to me on LinkedIn with all of these and any other feedback you have on this series 😁
