Nighttime is when the effect of humans on the environment is especially pronounced. Outside of wildfire, most nighttime lighting is from artificial sources such as street lights.
Satellites now are able to captured illumination of the Earth’s surface and in some areas, the contrast is significant.
As artificial lights cover more and more of the Earth, nighttime darkness is becoming increasingly rare.
What is light pollution?
Light pollution, defined as the “inappropriate or excessive use of artificial light” is increasing worldwide. Light pollution doesn’t just affect urban areas.
Sky glow, the brightness of the night sky as a result of nearby artificial light pollution, affects an estimated 80% of the world’s population. Glare, from the direct shining of artificial lights is another problem area.
Light pollution can have deleterious effects on both human and wildlife populations by affecting diurnal rhythms. The disruption of the circadian rhythm has been shown to impact wildlife migration as well as impacting sleep patterns, feeding schedules, and reproductive cycles.
Light pollution also impacts human quality of life.
Mitigating Light Pollution
There are efforts to combat excessive nighttime lighting. For example, some cities are swapping out light fixtures that angle lights down instead of shining up into the night sky.
The International Dark-Sky Association works with nations and organizations to create dark sky sanctuaries. These areas have prioritized access to night time views. Niue was the first nation to receive the Dark Sky Nation status.
Satellite View of the Earth at Night
The growth of night lights is most visible in satellite pictures of the Earth and in photos taken from the International Space Station.
Known as the Black Marble (as opposed to the daytime Blue Marble), NASA updates a composite view of the Earth at Night occasionally. The last composite view of the Earth’s night lights basin 2016.
United States at Night
This composite image of the United States at night was created in 2012 by NASA.
The level of light pollution varies across the United States, depending on the density of the area.
According to a study done in 2016, 99 percent of the population of the United States lives under light-polluted skies, which means that the vast majority of Americans do not have access to a really natural view of the night sky. Furthermore, 80% of Americans are unable to see the Milky Way from where they live.
Night Lights Over New York
The northeastern part of the United States is very densely populated. New York City is home to almost nine million residents. This night time view of major cities along the northeastern coast of the United States was taken aboard the International Space Station.
The cities of New York (NY), Newark (NJ), Philadelphia (PA), New Haven (CT), and Hartford (CT) are visible in this photo. The thin line of lights of 1-95 is also visible. The dense urban area spans 200 miles (300 kilometers) from Hartford to Philadelphia.
Holiday Lights Over Texas and Louisiana
Nighttime lighting increases significantly in the United States around the Christmas and New Year’s holiday season. A 2015 study on holiday lights found that, when compared to the rest of the year, evening lights in many major U.S. cities shine 20 to 50 percent brighter between Christmas and New Year’s.
NASA researchers analyzed the change in light intensity in the period between Thanksgiving and New Year’s as compared to other times of the years. This satellite image has the mapped results of changes in light intensity over parts of Texas during the month of December (for the years 2012 and 2013) compared to the monthly average from 2012 to 2014 excluding those months.
Green coloring indicates locations where light usage grew in December, yellow indicates areas where light usage remained unchanged, and red indicates areas where light usage decreased.
The researchers also found that holiday-light related increases were more pronounced in suburban areas compared to urban areas.
South America’s Atlantic Coast
Night lights from the South American cities of Rio de Janeiro, São Paulo, and Buenos Aires can be seen in this satellite image taken in 2012.
Rail Station Legacy Influences Argentina’s Night Lights
A view of Argentina’s night lights reveals an interesting pattern. Argentina’s night lights are evenly space out in lines across the country. This formation is a legacy from when these towns sprung up around railway stations.
These stations were established about every 20 to 30 miles (30 to 50 kilometers). Developments rose around these stations, which explains the regularly and linearly spaced lights visible on satellite imagery of Argentina today. Also visible is a segment of the Pan-American Highway around San Luis.
This Suomi satellite image shows the night lights of the Northern Europe countries of Finland, Sweden, Norway, Denmark, and Russia.
Volcanic Eruption at Night
There are some sources of natural nighttime light. The flowing lava from the Cumbre Vieja volcanic eruption on La Palma in the Canary Islands was visible at night from the International Space Station. Lights from nearby Los Llanos and El Paso can also be seen in the photo.
Bangkok, Thailand Night Lights
This oblique photo from the International Space Station shows Thailand at night. Bangkok’s urban lights dominate the area, with neighboring cities’ lights along the Gulf of Thailand.
Green lights from fishing boats can be seen out in the ocean. The green lights draw plankton and fish to the surface which in turn attracts squid which the fishing boats then capture.
Night Lights at the India – Pakistan Border
In the Indo-Gangetic Plain, a line of orange-hued lights marks the border between northern India and northern Pakistan. The floodlights, as well as fencing, were constructed by the Indian government to deter smuggling and arms trafficking.
The border’s brightness is so bright that it can be seen from the International Space Station, where this image was taken in August of 2011.
North Korea at Night
One country that stands out for its lacks of night time lights is North Korea. On maps depicting nighttime lights, North Korea’s whole country is a large black area.
Due to the collapse of the Soviet Union in the early 1990s, a cheap source of fuel was no longer available, and the country now descends into darkness with the sunset, with the exception of an island of light where Pyongyang, the capital, is located. According to the U.S. Energy Information Administration, North Korean’s electricity consumption dropped from 33 billion kilowatthours (BkWh) in 1990 to 16 BkWh by 2000.
The satellite image below shows the stark difference between night time lights in North Korea compared to South Korea. Only a small amount of lighting, mostly centered on the capital of Pyongyang can be seen in North Korea. South Korea is gleaming with artificial lights across the country.
Lights from fishing boats can be seen in the Yellow Sea and the Sea of Japan.
Falchi, F., Cinzano, P., Duriscoe, D., Kyba, C. C., Elvidge, C. D., Baugh, K., … & Furgoni, R. (2016). The new world atlas of artificial night sky brightness. Science advances, 2(6), e1600377. DOI: 10.1126/sciadv.1600377
Light pollution – Night skies. (n.d.). NPS.gov (U.S. National Park Service). https://www.nps.gov/subjects/nightskies/lightpollution.htm
Román, M. O., & Stokes, E. C. (2015). Holidays in lights: Tracking cultural patterns in demand for energy services. Earth’s future, 3(6), 182-205. https://doi.org/10.1002/2014EF000285