The Bortle Scale and Light Pollution
The Bortle Scale is used by astronomers to rate the darkness of our skies. It ranges from 1 (darkest) to 9 (brightest). For most of us, our daily lives are spent beneath a radiance level of between 5 and 8 and rarely venture into areas ranked 3 or darker- and what a shame that is.
Light pollution, while a testament to our technological advances, has blanketed our view of the universe and decoupled our relationship with the cosmos. For the millions of people living in areas where less than 20 stars can be seen in the night sky, it is practically impossible to imagine a natural sky blanketed with upwards of 2,500 stars backed by great ribbons of billions of stars which can be found in our Galaxy: The Milky Way.
What are the effects of light pollution?
From a research perspective, studies have demonstrated that our overuse of artificial light at night can increasingly be linked to sleep disorders, diabetes and cancer. Ecologically, habitats are disturbed and species are forced to adapt to or flee from this unnatural phenomenon. Environmentally, it is a huge waste of energy. Socially, increased light pollution can lead to a decrease in safety and security.
From a psychological perspective, the lack of a brilliant dark sky can affect our humility. Without the nightly reminder of a vast cosmos, it is easy to forget how small we are, how insignificant. It is simple to imagine that we are the centre of all things when confined to a solitary closed ecosystem, this tasks gets harder when faced with the immensity of the universe before us.
Before we invented civilisation, our ancestors embraced the darkness of space, wondered at the stars and contemplated the universe. Today, we immerse ourselves in artificial light; a lot of which is unnecessary and the result of bad habits. If we shield, downgrade or time our existing lighting infrastructure we could open the wonders of the night sky back up again.
While artificial light has undoubtedly enriched our lives, the same has always been true of darkness- we do not need to be afraid of it.
In the words of Sarah Williams “I have loved the stars too fondly to be fearful of the night.”