Show:
Impact on Humans
Types
Impact on Environment
Bortle Scale
200

Artificial light at night (ALAN) disrupts this biological process, often termed the "internal clock," which regulates sleep, metabolism, and hormone production

What is the Circadian rhythm?

200

Over-illumination light pollution results in the overconsumption of this energy carrier, which is the organized flow of charged particles.

what is electricity?

200
Certain species of these web-building creatures avoid light-polluted areas, resulting in a passive form of artificial natural selection.

what are spiders?

200
At level 4 and under on the scale, this is visible in the night sky - the galaxy in which we live.

what is the Milky Way?

400

Extreme night sky pollution is linked to a 34% increase in the likelihood of developing which cancer that begins in mammary tissues?

what is breast cancer?

400

Blinding, disability, and discomfort are the three categories of this type of light pollution, which shares its name with an intense, angry stare.

what is glare?

400
These animals might mistake artificial light for natural horizon light, which they rely on to reach the ocean after hatching.

what are turtles?

400

This special administrative region of China and port city, which is cited to be the most light polluted city in the world, factors at a 9 on the scale.

what is Hong Kong?
600
Night sky obstruction suppresses the production of which hormone, which is often taken as a supplement to improve sleep quality?

what is melatonin?

600

One type of light pollution derives from these objects, which orbit planetary bodies and send information back to Earth.

what are satellites?

600

Light pollution disrupts this process that certain bird species complete seasonally for access to resources.

what is migration?

600
At level 0, this "light" - named for the fact it forms a band that passes through constellations like Aries, Leo, and Capricorn - is clearly visible.

what is zodiac(al) light?

800

As of 2024, the amount of money, in USD, lost globally per year due to the impairment of ecosystems as a result of light pollution. (leeway given)

what is $3.36 trillion?

800

This is the only form of light pollution explicitly prohibited by the city of New Orleans, sharing its name with a verb that means to tread on someone's property without permission.

what is trespass?

800

Night-blooming flowers are threatened by light pollution because of the interference to these nocturnal, winged, insect pollinators

what are moths?

800

This southeastern Asian country factors at a 9 on the scale - the most light polluted country in the world.

what is Singapore?
1000

The percent of Americans living under light-polluted skies 10% brighter than natural darkness

what is 99%?

1000

The official term given to the illumination of the night sky as a result of light pollution

what is skyglow?

1000

Light pollution can prevent zooplankton from eating algae in lakes, causing this phenomenon that suffocates fish and lowers water quality.

what is (an) algal bloom?

1000

Bortle first published his scale in this magazine, which covers all aspects of amateur and professional astronomy and features Diana Hannikainen as editor-in-chief

what is Sky & Telescope?