Light Pollution's Impact On The Eclipse Over La Serena

Light pollution, caused by the diffusion of artificial light, is a growing problem in many parts of the world, including La Serena, Chile. The phenomenon results from light beams that do not aim downward and light radiation at wavelengths beyond the human eye's perception. While light pollution does not affect the brief moments of totality during an eclipse, it can impair stargazing and astronomy. La Serena, a city of approximately 450,000 people, is known for its clear skies and astronomical observatories. However, light pollution from the city has diminished the darkness of the night sky and impacted the visibility of celestial bodies. The artificial irradiation from La Serena has affected the surrounding region, including the Elqui area, which is considered one of the clearest skies on the planet. The Chilean government is now focusing on addressing light pollution by creating emission standards and seeking to protect the quality of the country's renowned night skies.

La Serena's light pollution impact on observatories

La Serena, a city of 450,000 people in Chile's Coquimbo region, is known for its clear skies and astronomical observatories. However, light pollution from the city is becoming an increasing problem for these observatories.

Light pollution, caused by the diffusion of artificial light, creates a glow in the night sky that diminishes the darkness and makes it harder to see stars and other celestial bodies. In the case of La Serena, this pollution is affecting nearby observatories, including the Cerro Tololo scientific observatory, which is located over 2,000 meters above sea level. While the cities themselves cannot be seen from the observatory, the light beams that are dispersed at this altitude are still captured, disrupting the ability to view the sky clearly.

The main sources of light pollution in La Serena are public electricity supply networks of illumination that do not have properly designed screens to direct the light downward and prevent dispersion into the sky. Indiscriminate use of globe-like illumination without screens, lack of control over decorative lighting in buildings, commercial ads with poor lighting, and the use of mercury vapour lamps all contribute to the problem.

The impact of La Serena's light pollution extends beyond the immediate area. The city was found to be the largest source of artificial sky brightness at three other sites in the region: Fray Jorge National Park, Las Campanas Observatory, and Collowara Astrotourism Observatory. This highlights the need to reduce light pollution in La Serena to preserve the dark skies that are crucial for astronomical observations.

To address this issue, the Chilean government, with support from regional governments, is working on creating emission standards to regulate light pollution and protect the quality of the night sky. These efforts are crucial to ensure that the Coquimbo region remains a prime location for astronomy and to prevent future deterioration in the quality of Chile's northern skies.

The effect of artificial light on the night sky

Light pollution is the human-made alteration of outdoor light levels from those occurring naturally. It is caused by the diffusion of artificial light, which creates a glow in the sky at night. This phenomenon is not limited to a few places but occurs all over the world.

The main cause of light pollution is the use of public electricity supply networks of illumination that do not have properly designed screens to direct the light where it is needed and prevent its dispersion into the sky. This includes the indiscriminate use of globe-like illumination without screens, a lack of control over decorative lighting in buildings, and commercial ads with poor lighting. Mercury vapour lamps (LVM) are also a significant contributor, as their emission band is very wide, with some lines coinciding with the nebula and emitting light outside the visible spectrum.

Light pollution has several negative consequences. Firstly, it diminishes our ability to observe the night sky and celestial bodies. Astronomical observatories, in particular, are affected by light pollution, which reduces the clarity needed to capture events in the galaxy. Light pollution also has economic impacts, with the International Dark-Sky Association estimating that one-third of all lighting is wasted at an annual cost of $2.2 billion in the US alone.

Furthermore, light pollution has been linked to various health issues. Darkness is essential to our biological welfare, as it is a part of our circadian rhythms, which are disrupted by the presence of artificial light at night. This disruption has been associated with sleep disorders, depression, hypertension, attention deficit disorder, obesity, diabetes, and heart disease. Additionally, light pollution can affect the production of melatonin, a potent antioxidant and anti-carcinogen responsible for regulating metabolism and immune responses. Exposure to bright light at night can halt its production, and lowered melatonin levels have been linked to rising breast cancer rates in the developed world.

Light pollution also has ecological consequences. Wherever human light spills into the natural world, it affects some aspect of animal life, such as migration, reproduction, hunting, and feeding. For example, sea turtle hatchlings instinctively head towards the brightest source of light, which used to be starlight reflecting off the ocean. However, due to coastal cities' bright lights, the hatchlings become disoriented and fall prey to dehydration and predation, leading to significant hatching losses.

La Serena's light pollution in relation to the 2019 solar eclipse

On July 2, 2019, a total solar eclipse occurred at the ascending node of the Moon's orbit. The eclipse was visible from the southern Pacific Ocean, east of New Zealand, to the Coquimbo Region in Chile and Central Argentina at sunset. The path of totality included the cities of La Serena and La Higuera in the Coquimbo Region.

La Serena, a city in northern Chile, is known for its clear night skies and is the world's first International Dark Sky Sanctuary. The region's dark skies are a natural wonder that draws tourists from all over the world. As such, La Serena was filled with tourists during the 2019 eclipse.

However, light pollution is a common problem that threatens the region's natural beauty. As tourism to the region increases, so does the threat of light pollution. To address this issue, the Chilean government has prioritised protecting the dark skies of northern Chile through regulation and education.

During the 2019 eclipse, the path of totality travelled over areas with low levels of humidity and light pollution, allowing for very good observations. The European Southern Observatory in La Silla, Chile, experienced totality, and tickets to view the eclipse from there were sold for US$2000 each. Approximately 300,000 people visited La Serena to witness this astronomical event.

The impact of light pollution on the Milky Way

Light pollution, caused by the diffusion of artificial light, has a detrimental impact on the visibility of the Milky Way and the overall quality of the night sky. The phenomenon is not limited to certain places but affects various regions worldwide, including the Elqui area in Chile, which boasts the clearest skies on the planet. Light pollution results from the use of public electricity supply networks with inadequate screens, allowing light to disperse into the sky instead of being directed downward. This issue has led to a "cultural loss of unprecedented magnitude," as described by scientists, where the Milky Way is no longer visible to one-third of humanity.

The effects of light pollution extend beyond the impairment of stargazing and astronomy. It has biological consequences on both wildlife and human health. For example, sea turtle hatchlings rely on moonlight reflecting off wave tops to navigate to the sea, but artificial lighting disorients them, leading to high mortality rates. Similarly, artificial lighting disrupts the reproductive cycles of species like the tammar wallaby, affecting their fertility and offspring's survival.

Light pollution also impacts human health by interfering with circadian rhythms and altering biochemical rhythms. The excessive use of indoor and outdoor lighting, such as bright bathroom lights and intense streetlights, can disrupt melatonin production and circadian regulation, contributing to health issues like obesity, heart disease, diabetes, depression, and cancer.

Furthermore, light pollution severs our connection to the night sky, which has been a source of inspiration for artists, musicians, and poets throughout history. As Brian May, astrophysicist and lead guitarist of Queen, laments, "We, in our ceaseless dash to make money and cover the world with concrete, have lost this priceless treasure."

To address light pollution, measures such as shielded street lighting, motion-activated lights, and cut-off times for illuminating buildings have been proposed. Implementing these solutions can reduce energy consumption, protect ecosystems, and restore our connection to the night sky, allowing us to appreciate the awe-inspiring beauty of the Milky Way and beyond.

Efforts to reduce light pollution in La Serena

Light pollution in La Serena, Chile, has been a growing concern over the last decade due to the region's rapid population growth and development. The artificial light emanating from La Serena and the neighbouring city of Coquimbo has significantly impacted the darkness of the night sky and the visibility of stars and other celestial bodies. This is particularly problematic for the region's astronomical observatories, which rely on dark skies for their research and operations.

To address this issue, the Chilean government, supported by the regional governments of Antofagasta, Atacama, and Coquimbo, is working to establish emission standards to regulate light pollution and protect the quality of the country's skies. The Universidad de La Serena is also actively involved in efforts to reduce light pollution, collaborating with organisations such as NOIRLab and Fundación Cielos de Chile to monitor sky brightness and provide scientific advice on lighting installations.

One of the key strategies to mitigate light pollution in La Serena is the implementation of properly designed screens and shields for light sources. This includes addressing the indiscriminate use of globe-like illumination without screens and the lack of control over decorative lighting in buildings. By directing light downwards and preventing its dispersion into the sky, these measures can significantly reduce light pollution.

Additionally, organisations such as the Arizona Astronomy Consortium (AzAC) have been advocating against the conversion of conventionally illuminated billboards to digital LED billboards, which can contribute significantly to light pollution. Educational initiatives and outreach campaigns are also being conducted to raise awareness about the importance of dark skies and the impact of light pollution.

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