Frequently Asked Questions:

Light pollution—what is it and why is it important to know?


Glaring lights can actually reduce visibility. Image Credit: International Dark-Sky Association

Light pollution is excessive and inappropriate artificial light. The four components of light pollution are often combined and may overlap:

  • Urban Sky Glow—the brightening of the night sky over inhabited areas.
  • Light Trespass—light falling where it is not intended, wanted, or needed.
  • Glare—excessive brightness which causes visual discomfort. High levels of glare can decrease visibility.
  • Clutter—bright, confusing, and excessive groupings of light sources, commonly found in over-lit urban areas. The proliferation of clutter contributes to urban sky glow, trespass, and glare.

For most of Earth’s history, our spectacular universe of stars and galaxies has been visible in the darkness of the night sky. From our earliest beginnings, the vast spectacle arrayed across the dark sky has inspired questions about our universe and our relation to it. The history of scientific discovery, art, literature, astronomy, navigation, exploration, philosophy, and even human curiosity itself would be diminished without our view of the stars. But today, the increasing number of people living on earth and the corresponding increase in inappropriate and unshielded outdoor lighting has resulted in light pollution—a brightening night sky that has obliterated the stars for much of the world’s population. Most people must travel far from home, away from the glow of artificial lighting, to experience the awe-inspiring expanse of the Milky Way as our ancestors once knew it. Read more about Light pollution.

Top

What are examples of light pollution regulations, laws & policies?

Top

What are examples of effective lighting?

GlareBuster lighting fixture

GlareBuster lighting fixture

comparison of innefective ligting and effective lighting

Top

What are some ways to measure sky brightness?

Top

What are some models of sky brightness measurements?

Top

What are some ways light pollution affects wildlife?

Top

What are some ways light pollution effects our health?

Top

What are some outreach programs that promote dark skies awareness and how can we get involved in them?

The Hellenic Astronomical Society joining the international effort of the IAU Cornerstone Project “Dark Skies Awareness” has dedicated a national action in dark sky and environmental education, informing the citizens and authorities, through a relevant leaflet and organizing a national photographic contest for students, amateur and professional photographers.

More information can be found on the Hellenic Astronomical Society website.

More outreach programs

Top