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Light pollution from the city of Moscow shows how clear urban lights can make the nightly heaven. | Credit: Ivtorov via Wikimedia Commons
This article was originally published on The conversation. The publication has contributed the article to Space.com’s Expert Voices: Op-Ed & Insights.
Outdoor lighting for buildings, roads and advertising can help people see in the dark of the night, but many astronomers are increasingly worried that these lights can blind us to the rest of the universe.
An estimate from 2023 showed that the speed of light produced by people increases by no less than 10% per year.
I am an astronomer who is chairman of a standing committee for astronomical location protection for the international astronomical trade union sponsored working groups that study on the ground -based light pollution.
My work with these groups is aimed at the idea that lights of human activities are now influencing astronomical observatories on what used to be on the far mountain tops.
Warm science in the cold, dark night
While running telescopes such as the Hubble Space Telescope or the James Webb Space Telescope, researchers give a unique picture of the cosmos, especially because they can see light blocked by the atmosphere of the earth-staying telescopes by the advanced discovery.
Telescopes on the ground catch light with gigantic and precise focusing mirrors that can be 20 to 35 feet (6 to 10 meters) wide. Moving all astronomical observations to space to escape from light pollution would not be possible, because space emissions have much higher costs and so many large land -based telescopes are already in operation or under construction.
There are 17 telescopes based on the ground all over the world with primary mirrors so large or larger than webb’s 20-foot (6-meter) mirror, and three more under construction with mirrors planned to span 80 to 130 feet (24 to 40 meters).
The newest telescope that is currently starting its scientific mission, the Vera Rubin Observatory in Chile, has a mirror with a 28-foot diameter and a 3-gigapixel camera. One of the missions is to map the distribution of dark matter in the universe.
To do that, it will collect a sample of 2.6 billion galaxies. The typical galaxy in that monster is 100 times weaker than the natural glow in the night air in the atmosphere of the earth, so this rubin observatory program depends on almost total natural darkness.
Any light that is spread at night – road lighting, building lighting, billboards – would add blinding and noise to the scene, so that the number of galaxies that Rubin can measure considerably in the same time can considerably measure, or greatly increase the total exposure time that is needed to get the same result.
The Vera Rubin Observatory is located in the mountains of Chile to prevent light pollution. | Credit: Rubin Observatory/NSF/Aura/B. Quint via Wikimedia Commons
The LED Revolution
Astronomers specifically give artificial light in the blue -green range of the electromagnetic spectrum, because it used to be the darkest part of the nightly sky. A decade ago was the most common outdoor lighting of sodium vapor lamps. They produced an orange-pink glow, which meant that they remained very little blue and green light.
Even observatories relatively close to the growing urban areas that were naturally dark in the blue and green part of the spectrum, which made all kinds of new observations possible.
Then came the Solid-State LED lighting revolution. These lights postpone a wide rainbow in color with very high efficiency – which means that they produce a lot of light per Watt electricity. The earliest versions of LEDs released a large part of their energy in the blue and green, but the advancing technology now gets the same efficiency with “warmer” lights that have much less blue and green.
Nevertheless, the previously unspoilt darkness of the night sky now has much more light, especially in the blue and green, of LEDs in towns and villages, lighting roads, public spaces and advertisements.
The wide output of color of LEDs influences the entire spectrum, from ultraviolet to deep red.
In 2019, the US Department of Energy ordered a study that predicted that the higher energy efficiency of LEDs would mean that the amount of power used for lights at night would fall, with the amount of light that remains approximately the same.
But satellites who look at the earth just reveal that is not the case. The amount of light increases steadily, which means that cities and companies were willing to keep their electricity accounts about the same as improves energy efficiency and simply get more light.
The many telescopes involved in the Kitt Peak National Observatory (KPNO), located in the Quinlan Mountains in Arizona. | Credit: KPNO/Noirlab/NSF/AURA/T. Slovinský via Wikimedia Commons
Natural darkness in retreat
As human activity spreads over time, many of the remote areas that observatories are less remote. Light domes from large urban areas brighten up the dark sky at Mountaintop Obsoleschtop Observatoria up to 200 miles (320 kilometers) distance. When these urban areas are adjacent to an observatory, the addition to the Skyglow is much stronger, making the weakest galaxies and stars much more difficult to detect.
When the Mt. Wilson Observatory was built in the Angeles National Forest near Pasadena, California, in the early 1900s, it was a very dark site, considerably far from the 500,000 people living in Greater Los Angeles. Nowadays, 18.6 million people live in the LA area and urban proliferation has civilization much closer to Mt. Wilson brought.
When Kitt Peak National Observatory was first under construction in the late 1950s, it was far from Metro Tucson, Arizona, with his population of 230,000. Nowadays that area houses 1 million people, and Kitt Peak is confronted with much more light pollution.
Even telescopes in dark, more remote regions such as North Chili or West-Texas-Light pollution due to industrial activities such as Open-Pit mining or oil and gas facilities.
The case of the European Southern Observatory
An interesting modern challenge is confronted with the European Southern Observatory, which operates four of the world’s largest optical telescopes. Their site in the north of Chile is very remote and is nominally covered by strict national regulations that protect the dark sky.
AES Chile, an energy supplier with strong support from American investors, announced a plan in December 2024 for the development of a large industrial factory and transport hub close to the observatory. The plant would produce liquid hydrogen and ammonia for green energy.
Although formally in accordance with the national lighting standard, the fully built operation could spread sufficient artificial light in the nocturnal sky to change the pristine darkness of the current observatory into a state comparable to some of the old observatories now near large urban areas.
This light pollution can mean that the facility does not have the same ability to detect and measure the weakest galaxies and stars.
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Light pollution does not only affect observatories. Nowadays, around 80% of the world’s population cannot see the Melkweg at night. Some Asian cities are so clear that the eyes of people who walk outside cannot be visually adjusted.
In 2009, the International Astronomical Union stated that there is a universal right to starlight. The dark night sky is from all people-deeply beauty something that you don’t have to be astronomer to appreciate.
This article has been re -published from The conversation Under a Creative Commons license. Read the Original article.
