The stars are becoming invisible to our eyes faster than we thought.

light pollution this is a serious problem that is not always given due attention. It’s hard to imagine that something as essential and abstract as light can infect. However, this happens on many levels. It prevents you from seeing the sky both amateur and professional astronomyand in turn can affect living beings in very different ways. For this reason, attempts have been made for many years to track how this pollution develops. The problem is that this has been done with satellites equipped with sensors, which, according to a new study published in The sciencethey underestimated the problem.

In this new study, published citizen science data. That is, information taken by non-scientists who volunteer to help researchers in their task, thus covering a large area of ​​the planet.

In this case, they participated over 51,000 citizen scientistsbetween 2011 and 2022. Everyone had to fill out a series of questionnaires, the analysis of which led to very disturbing conclusions: light pollution progresses with exchange rate much more than the satellites predicted. There are more and more reasons to take action, so it will now be necessary to continue to raise awareness of this.

The problem of light pollution

In 1994, the Los Angeles earthquake left thousands without electricity. Shortly thereafter, people began calling 911, frightened by the silver streak that had opened up in the sky, as majestic as it was terrifying. They believed that the earthquake split the firmament. But really they were just watching Milky Way. Usually their city was so illuminated that they never had a chance to see our galaxy.

This story is always told to draw attention to how far light pollution can go. And the thing is, it’s not just about big cities like Angels. Many people today, residents of much smaller cities, deny that they have ever seen this trail of silver dots tracing the sky. It also cannot distinguish constellations clearly. In fact, they have difficulty distinguishing some of the stars. The marvelous, jewel-studded sky that our ancestors enjoyed just by looking at the sky has become a luxury that only a few can enjoy. This alone is already a problem, but it is nothing more than a start.

artificial city lighting it radiates such a level of brightness into the sky that astronomers also cannot see it clearly to do their job. Even some observatories located at a great distance from cities have to suffer from the glare they throw into the sky.

But there is more. The animals that the Moon directs into motion are confused with the thousands of luminaries that illuminate the cities, so they confused, lost and sometimes dead. The growth of some plants that follow their own heart rhythms. And even human health suffers from exposure to excessive lighting at night. There are many reasons why light pollution is a problem. To top it off, we now know that this is happening way too fast.

NOIRLab/NSF/AURA, P. Marenfeld

New data thanks to cooperation with citizens

This study was conducted using data from the Globe at Night project led by US National Science Foundationfor the purpose of measuring light pollution without leaving the Earth.

For this, two approaches were compared. On the one hand, they took satellite data measured in 2014. And, on the other hand, they were looking for volunteers for direct observation of the sky from different parts of the world. Total participated 51,351 people living in 19,262 different parts of the world. They all had to do the same thing: look at the sky and choose from several images from an online survey the one that most closely resembled what they had seen. Therefore, it was something very simple, requiring no knowledge of astronomy.

Once the data was collected, it was analyzed together and tested to see what increase in annual brightness each area corresponds to. They concluded that it would 6.5% in Europe and 10.4% in North America. This is much higher than what was concluded with satellites. Thus, the situation is more dramatic than previously thought. So much so that, as the authors of the study explain in a statement, if a child born today can see 250 stars, then on their 18th birthday they will only be able to see 100 stars at the same point.

Why is citizen science more useful for measuring light pollution?

There are two reasons why the authors of this study believe that these volunteers were measuring light pollution. better than satellites

On the one hand, sensors located in space measure the emitted light. up. However, light pollution is also caused horizontal lights. That is, the one that comes out of illuminated signs or facades, for example. Ideally, use lampposts pointing down, as this eliminates both.

People looking at the sky from Earth can see how the horizontal light hinders observation. Therefore, a more accurate calculation of the increase in brightness can be made.

On the other hand, glare from blue light causes the most light pollution. In recent years sodium lampsmore orange, have been largely replaced blue LEDs. And from space, this is more difficult to measure, since sensors on satellites that can cover the entire globe are much less sensitive to these wavelengths. Instead, people on Earth will experience first hand how this blue light obscures the vision of the stars.

So while satellites have already given us an idea of ​​the severity of the problem, we now know it’s even worse. If nothing is done to fix this, in a short time, a terrible number of people on this planet will be living, oblivious to the spectacle of the sky above their heads. And it won’t be the worst.