Earth at Night

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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.

Night pollution obscure the night sky. In the top photo, the stars in the night sky over the Inglesby area of the park are dimmed due to the artificial lights of Jensen and Vernal Utah. In the bottom photo the night sky shows with lots of stars including the Milky Way over Blue Mountain and the Green River Campground. Artificial lights from the restrooms light up the campground. Photos: Inglesby and Green River Campground, NPS/Jake Holgerson, Dinosaur National Monument, public domain.
The night sky is obscured by night pollution. The artificial lights of Jensen and Vernal Utah have diminished the stars in the night sky over the Inglesby portion of the park in the top photo. The night sky is filled with stars in the bottom frame, featuring the Milky Way over Blue Mountain and the Green River Campground. The campground is illuminated by artificial lights from the restrooms. Photos: Inglesby and Green River Campground, NPS/Jake Holgerson, Dinosaur National Monument, public domain.

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.

Before and after pictures of replacement lighting at the 6th Street Bridge over the Los Angeles River. The image on the right shows replaced light fixtures that angle the light down instead of sideways and upwards. Photos: City of Los Angeles.
Before and after shots of the 6th Street Bridge over the Los Angeles River’s replacement lighting. The image on the right depicts replaced light fixtures that direct light downward rather than sideways and above. Photos: City of Los Angeles.

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.

Black Marble

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.

A composite view of the Earth's lights at night by NASA.
Black Marble, 2016. NASA, public domain.

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.

Composite satellite image of the United States at night.
Composite satellite image of the United States at night, 2012. Image: NASA.

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.

Photo taken at night from the International Space Station showing New York and New Jersey.
View of northeastern United States at night from the International Space Station. Image: NASA, 2017.

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.

Map showing the increase in light intensity at night over Texas on a satellite image. The darker green areas have a greater increase in light intensity.
Map showing the increase in light intensity at night over Texas on a satellite image. Image: NASA.

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.

Night light satellite image of South America’s Atlantic Coast.
Night light satellite image of South America’s Atlantic Coast, 2012. Image: NASA.

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.

Satellite image of night lights in Argentina.
Argentina’s towns are regularly spaced out due to railway stations. Image: NASA.

Northern Europe

This Suomi satellite image shows the night lights of the Northern Europe countries of Finland, Sweden, Norway, Denmark, and Russia.

Satellite image of Northern Europe at night.
Satellite image of Northern Europe at night. Image: NASA, 2016.

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.

Photo from the International Space Station showing glowing lava at night.
This photo from the International Space Station shows lava flowing brightly at night from the Cumbre Vieja volcano on La Palma in the Canary Islands. Image: NASA, public domain.

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.

Photograph from the International Space Station showing Bangkok, Thailand at night.
Photograph from the International Space Station showing Bangkok, Thailand at night. Source: NASA.

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.

Photo from the International Space Station showing the bright lights of Bangkok, Thailand and green lights from fishing boats.
The bright night time lights of Bangkok, Thailand and green lights from fishing boats. Source: NASA.

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.

A photo taken from the International Space Station showing the night lights over India and Pakistan.
The orange-lit border between India and Pakistan can be seen in this photo shot from the International Space Station of the Indo-Gangetic Plain. Source: NASA, August 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.

A satellite image showing the Earth at night for North and South Korea.
Night time lights in North Korea and South Korea. Source: NASA.

References

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 advances2(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 future3(6), 182-205. https://doi.org/10.1002/2014EF000285

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