Light pollution obscures our view of the stars. Here’s how you can help get it back

A study by the Globe at Night project – a citizen science program that includes more than 50,000 observations from volunteers around the world – found that the brightness of the night sky has increased by 7 to 10 percent per year over the past decade. the past.

We talked to Dr. Greg Brownan astronomer at the Royal Observatory Greenwich, about what the process means for humans, astronomers and animals, and if it could be changed.

How bad is the situation? Are we looking at a potential situation where future generations will not be able to enjoy stargazing without visiting designated sites?

It is a great shame that so many people are denied a view of the night sky. In the planetarium we run here at the Royal Observatory, we often start some of our programs with an estimate of the current light pollution around London. Even in our relatively dark place in the middle of the park we still have to deal with Canary Wharf and large parts of the city around us. When we compare that level of light pollution to what the night sky would look like in a dark sky, the difference is huge. No doubt that will affect our appreciation of the night sky.

The brightest things in space [such as planets] they will be more visible than any reasonable measure of light pollution we can achieve. But few objects in the sky, the constellations in the Milky Way, for example, are already impossible to see from urban areas let alone urban centers. So, yes, light pollution greatly impairs the average person’s ability to observe the universe.

So how do we measure the extent of light pollution?

With some difficulty. Much of the previous research has been done with satellites that are great for detecting red light, but struggle with blue. This is a problem since modern light pollution tends to be blue light due to the replacement of sodium lamps, for example in street lights, with LEDs. So many studies these days have to be done from the ground up to be able to do that. This is where citizen science comes into play in this project. There are not enough people studying this genre in the world. So there has to be some contribution from the general public to make up that deficit.

When did this tradition begin?

Light pollution has become a growing problem since the 1970s. It has been accelerated in modern times by urban expansion and urbanization, and by people moving from rural areas to cities. Switching to LED lights was thought to be a way to help with this problem because more efficient lights mean you need less. But of course there is also the opposite argument which is that with more efficient lights you can have more for the same amount of power and therefore make the problem worse.

How does light pollution affect astrology?

When it comes to astronomers, most observations are made in specially selected areas of the dark sky. So we are talking about the almost uninhabited places of the world, like the Atacama Desert in Chile or the mountain peaks of the Canary Islands. The effect of light pollution is not great in those areas because they are far away from cities in the first place. It is one of the reasons why they were chosen. That said, not all observatories are well placed that far and there are issues with light pollution that goes beyond what we put into the sky from the ground. In the same way, there are problems with the increasing number of satellites that pollute the images from professional centers around the world, which are however related, but as issues of light pollution.

Can light pollution also affect our health?

Really. As humans we tend to stay awake during the day and sleep at night. The more light we project into our Sky at night, the harder it is for our bodies and body clocks to tell what time it really is. This leads to insomnia and issues arising from that – tiredness, fatigue, not to mention mental health. It’s also not just about the person. Wild animals have a big problem due to the increase in light pollution, the cycle of animals and prey, for example, in the past depended on the light of the Moon, because predators need light to be able to hunting But in fact, if it is always bright as if there is a full moon, then the predators have a constant way to be able to hunt other different animals there. That would be a serious problem for the diversity and balance of the biosphere.

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Is there anything we can do to reduce this trend?

There is definitely a need for careful planning when it comes to the use of lighting, especially street lights and city lights. Most of it will come down the road. Of course these lights are important. No one denies that the streets need lighting. The question is whether they need to be lit all the time and in the way it is being done now. Is there a way to make the lights turn on at certain times while they are in use by each person? Is there a way to direct that light down? The efficiency of overhead light is negligible. It doesn’t help anyone down. Anything that increases efficiency by directing that light down not only helps with light pollution, but helps with the specific purpose of those lights in the first place.

Is there anything individuals can do to help in this situation?

Make sure you don’t use too much lighting outside. If you have lights in your garden or driveway or anything near those types of lines, put them on motion sensors or only see them when you want to use them. . Also, looking for forward light, light directed down rather than up or in all directions, can greatly improve the amount of light pollution you produce.

About our expert, Dr. Greg Brown

Greg is an astronomer and communications scientist based at the Royal Observatory Greenwich.

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