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Starless Skies; a Consequence of Light Pollution in Cities

Energy waste, endangering biodiversity, negatively affecting plant and animal ecosystems and declining human health; these re some of the consequences of light pollution as urban cities grow. Light pollution comes mostly from artificial lighting in cities and has many negative consequences on human, plant and animal life. Persistent light negatively affects animals and plants from maintaining a healthy circadian rhythm of behaviours such as nourishment, reproduction and sleep. It also destroys the beauty of the skies at night, by reducing star visibility.

Light polluted skies: Why does it happen?

Light pollution does not affect the stars, but our perception of them. The natural starlight which allows us to stargaze competes with the excessive brightness of artificial light (light pollution) and as a result we are unable to perceive the light emitted by the stars. If a light source is not bright enough to contrast with the artificial brightness, we will not be able to perceive it. Sadly for us, this range includes most of the stars, the Milky Way, elusive Zodiacal Light and deep sky objects such as nebulae and galaxies.

The images below depict the Orion constellation as perceived in a high light pollution setting and the same constellation as perceived in a setting without any light pollution.

If you would like to see this simulation at various light settings visit

How can we reduce light pollution?

In order to preserve biodiversity, energy and the beauty of our night skies there are many solutions.

Installing motion sensors and timers is a great way to reduce pollution and ensure that artificial light is only on when a space is occupied and the light is needed. Additionally, bulbs should be covered and facing downward, to shine the light on the ground and not towards the sky. Finally, changing the hue of lighting to warm-white is a good alternative as it is energy efficient, and has a low light pollution effect while still illuminating greatly.

According to the USGBC, buildings can earn 1 LEED point in the Sustainable Sites category for Light Pollution Reduction. “The credit is intended to increase night sky access, improve nighttime visibility, and reduce the consequences of development for wildlife and people.” You can read more about the LEED credits available for Light Pollution Reduction:


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