Light Pollution Makes Night Sky 10% Brighter Each Year; How Does ALAN Worsen This Problem?

While specialists are familiar with certain effects of light pollution, it has been observed that the night sky has been becoming brighter at an unprecedented rate. This can be attributed to light pollution, mostly due to artificial light at night (ALAN).

Science News reports that through over 50,000 observations by citizen scientists, the night sky was seen to get 10% brighter each year from 2011 to 2022.

Light Pollution Brightens Up the Night Sky

Because of such figures, if a baby was born in an area where there are around 250 visible stars, the child would only get to see a hundred of them when the child turns 18 years old. This was reported by the researchers in the Science publication.

While this may be an issue in itself, the impacts of light pollution go way beyond this. Science News reports how excessive brightness may push birds that are migrating to fly into buildings, harm the health of individuals, disturb food webs, and even interrupt mating fireflies.

Connie Walker, an astronomer from the National Optical-Infrared Astronomy Research Laboratory in Tucson, notes how this serves as a call to action of some sort. Walker notes how people should think about how this impacts lives not just in terms of astronomy but also with regards to health. Other than that, it may even affect other animals that are incapable of standing up for themselves.

Walker is part of the Globe at Night project that began in the mid-2000s. The said project is an outreach program for connecting Chilean and Arizonian students. It currently has thousands of participants from all over the world. Contributors to this project study and compare the stars that they observe using maps of which stars can be seen at varying levels of light pollution. Their findings are then reported through an app.

Christopher Kyba, a physicist from the GFZ German Research Centre for Geosciences, expresses skepticism regarding the project. However, Science News reports that its strength lies in its massive numbers. Kyba and his team were able to study 51,351 pieces of inputted data taken from 2011 up to 2022.

Such data, mixed with the 2016 global atlas of sky luminance, enabled the team to find out how the night sky gets brighter by an average of 9.6% annually, from 2011 up to 2022.

The majority of the said increase got bypassed by satellites that collect global data regarding brightness. Science News reports that those assessments only observed a 2% brightness increase in the past decade.

Culprits Behind Skyrocketing Light Pollution

There are various reasons why this has been happening. Since the start of the 2010s, several outdoor lights have been changed to LED lights. While these LED lights are indeed energy and cost-efficient, they emit blue light with shorter wavelengths. This then dispersed particles into the atmosphere. It does this more than the typical orange light. This leads to heightened brightness and a glowing night sky.

Current satellites are not blue-light sensitive. Hence, they tend to underestimate LED-generated light pollution.

Light pollution researcher and astronomer John Barentine was not surprised by how satellites belittled this issue, but he was shocked by how belittled the concern was. He notes how the study reflects how specialists have been underestimating the global degree of light pollution.

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