by The lighting outdoors for buildings, streets and advertising can help people see in the dark of the night, but many astronomers are increasingly concerned that these lights could blind us to the rest of the universe.
An estimate of 2023 showed that the rate of people produced by humans increases by up to 10% per year in the night sky.
I am an astronomer that has led a permanent commission for the protection of the astronomical location for international astronomy that study floor -based light pollution.
My work with these groups has focused on the idea that lights from human activities now influence astronomical observatories on what was previously removed.
Hot science in the cold, dark night
While the surrounding of telescopes such as the Hubble World Commercial Telescope or the James WebB World Commercop researchers a unique view of the cosmos-especially because they can see light through the earth’s atmosphere–also based on the most modern discovery.
Telescopes on the floor catch light with gigantic and precise focus mirrors, which can be 20 to 35 feet (6 to 10 meters). It would not be possible to move all astronomical observations into space in order to escape light pollution, since space missions have much higher costs and so many large floor -based telescopes are already in operation or under construction.
All over the world, there are 17 floor-based telescopes with primary mirrors that are large or larger than the 20-foot mirror from WebB and three others under construction, with the mirrors that are planned that are intended to include 80 to 130 feet (24 to 40 meters).
The latest telescope, which is currently starting its scientific mission, has a mirror in Chile in Chile with a diameter of 28 feet and a 3-gigapixel camera. One of his missions is to map the distribution of dark matter in the universe.
It also collects a sample of 2.6 billion galaxies. The typical galaxy in this sample is 100 times weaker than the natural glow in the night air in the earth’s atmosphere, so this ruby observatory program depends on almost total natural darkness.
Every light that is scattered at night – road lighting, building lighting, advertising boards – would give the scene glare and noise, the number of galaxies that can be measured reliably or increase the overall exposure time significantly in order to achieve the same result.
The LED revolution
Astronomers especially take care of artificial light in the blue -green area of the electromagnetic spectrum, since the darkest part of the night sky used to be. A decade ago, the most common outdoor lighting of sodium steam lamps came. They produced an orange pink, which meant that they brought out very little blue and green light.
Even observatories relatively close to the growing urban areas had heaven, which in the blue and green part of the spectrum were naturally dark and made all types of new observations possible.
Then came the solid-LED lighting revolution. These lights triggered a wide rainbow of the color with very high efficiency – ie they produce a lot of light per watt electricity. The earliest versions of LEDs give a large part of their energy in blue and green, but the progress of the technology now receives the same efficiency with “warmer” shining that have much less blue and green.
Nevertheless, the formerly untouched darkness of the night sky now has a lot more light, especially in blue and green, from LEDs in cities and cities, lighting streets, public spaces and advertising.
The wide color output made of LEDs influences the entire spectrum, from ultraviolet to deep red.
The US Ministry of Energy commissioned a study in 2019 that predicted that the higher energy efficiency of LEDs would mean that the amount of electricity that is used for the lights would decrease, whereby the amount of light remained about the same.
But satellites that look at Earth show that this is simply not the case. The amount of light increases steadily, which means that cities and companies were ready to keep their electricity bills roughly the same as the energy efficiency improves and simply getting more light.
Natural darkness in retreat
Since human activity spreads over time, many of the remote areas in which taverns are less far away. Light domes from large urban areas illuminate the dark sky at mountain peaks observatories slightly up to 320 kilometers away. If these urban areas are due to an observatory, the addition to the glow of sky is much stronger, which captures the slightest galaxies and stars much harder.
When Mt. Wilson Observatory was built in the Angeles National Forest near Pasadena, California at the beginning of the 20th century, it was a very dark place that lived far from the 500,000 people in Große Los Angeles. Today 18.6 million people live in the LA area, and the urban spread has brought Mt. Wilson much closer.
When Kitt Peak National Observatory was under construction for the first time in the late 1950s, it was with its population of 230,000 far from Metro Tucson, Arizona. Today this area houses 1 million people, and Kitt Peak is faced with much more light pollution.
Even telescopes in darker, remote regions and northern chile or West Texas experience through industrial activities such as mining or oil and gas systems.
The case of the European southern observatory
An interesting modern challenge is to stand by the European southern observatory, which runs four of the world’s largest optical telescopes. Your location in Nordchile is very remote and is nominally covered by strict national regulations that protect the dark sky.
Aes Chile, an energy supplier with a strong US investor support, announced in December 2024 a plan for the development of a large industrial cultivation and a means of transport near the observatory. The plant would produce liquid hydrogen and ammonia for green energy.
Although the national lighting standard formally adhere to, the fully built company could scatter enough artificial light into the night sky to transform the flawless darkness of the current observatory into a state that resembles some of the legacy observatories near large urban areas.
This light pollution could mean that the facility does not have the same ability to recognize and measure the weakest galaxies and stars.
Light pollution does not only affect observatorios. Today, around 80% of the world’s population cannot see the Milky Way at night. Some Asian cities are so bright that the eyes of people who go outdoors cannot be adapted visually dark.
In 2009, the International Astronomical Union said that there was a universal right to Starlight. The dark night sky belongs to all people of human impressive beauty is something that you do not have to be a astronomer to appreciate it.
This article will be released from the conversation, a non -profit, independent news organization that brings you facts and trustworthy analyzes to help you understand our complex world. It was written by: Richard Green, University of Arizona
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Richard Green is connected to the International Astronomical Union and the American Astronomical Society and the Darksky International.
