A study conducted by the Globe at Night project, a citizen science program involving more than 50,000 observations by volunteers around the world, found that: Over the past decade, the brightness of the night sky has increased by 7-10% per year..
we talked Dr. Greg BrownRoyal Observatory Greenwich-based astronomer on what this trend means for laymen, astronomers and animals, and whether it can be reversed
How bad is the situation? Do future generations see a potential scenario in which they will not be able to see the stars without going to designated locations?
It is a great pity that many people are denied the view of the night sky. The planetarium we operate here at the Royal Observatory often starts the show with a current estimate. light Pollution around London. Even a relatively dark site in the middle of the park has to deal with Canary Wharf and the main parts of the surrounding city. When you compare that light pollution situation with what the night sky looks like from a dark sky site, the difference is huge.
brightest object in the sky [such as planets] It will become visible beyond any reasonable level of light pollution we can reach. However, dark objects in the sky, such as the array of stars in the Milky Way, are basically invisible from suburban areas, let alone urban centers. So yes, light pollution greatly hinders the average person’s ability to explore space.
So how do we measure the amount of light pollution?
with some difficulties. Much of the past research has been carried out using satellites that are good at analyzing red light but struggle somewhat with blue light. This is a problem because modern day light pollution tends to be a problem. blue light For example, as a result of replacing sodium lamps in street lighting with LEDs. So much research has to be done from the ground today to make up for it. That is where the citizen science perspective in this project comes from. There aren’t enough people in the world researching this sort of thing. So it needs some level of engagement from the general public to make up for that deficit.
When did this trend start?
Since the 1970s, light pollution has become a serious problem. In modern times, it is accelerated by urban expansion and urbanization, and rural-to-urban migration. It was thought that switching to LED lighting could be a way to solve this problem. can use more lighting, actually exacerbating the problem.
How much does light pollution affect professional astronomy?
When talking about professional astronomy, many of the observations are made from specially chosen dark sky locations. So we’re talking about relatively sparsely populated areas of the world, such as the Atacama Desert in Chile or the mountainside summits of the Canary Islands. That’s one of the reasons they were chosen. That said, not all observatories are far enough away from it, and light pollution is a problem, as well as the ones that are up in the sky from the ground. Equally, of course, is the growing number of satellites polluting imagery from professional observatories around the world. This is still a light pollution problem, albeit only tangentially related.
Can light pollution also affect our health?
absolutely. We humans are used to staying awake during the day and sleeping at night. The more light we let into the nighttime sky, the more difficult it becomes for our bodies and internal clocks to determine the actual time. Declining health. It’s not just a human problem either. Wildlife has been hit hard by increased light pollution. For example, predation-prey cycles were based on moonlight in the past. Because predators need light to hunt. But of course, when the moon is always as bright as the full moon, predators can always prey on a variety of other animals. This can be a serious problem for biosphere diversity and balance.
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Is there anything that can be done to slow this trend?
Indeed, the use of lighting, especially street lighting and city center lighting, requires careful planning. A lot of it comes down to directivity. Of course, this lighting is important. No one denies the need for street lighting. The question is whether they should always be lit and how they are currently done. Is there a way to turn the light on at a specific time when the individual is actually using it? Is there a way to point that light down? The efficiency of light going upwards is wasted. I am not helping anyone on earth. Anything that directs all that light to the ground and increases efficiency not only prevents light pollution, but also serves the specific purpose of these lights in the first place.
Is there anything an individual can do to improve this situation?
Make sure you are not overusing the lights outside. If you have lights in your yard, driveway, etc., either attach them to motion sensors or turn them on only when you actually want to use them. Using a directed light can greatly improve the amount of light pollution you are experiencing.
About our expert Dr. Greg Brown
Greg is an astronomer and science communicator based at the Royal Observatory, Greenwich.
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