00:008 out of 10 people in the world can no longer see the Milky Way, and in a hundred years only, it could be nothing more than a forgotten story.
00:07It is not the galaxy that disappears, but the cosmos that disappears.
00:11At the time of our grandparents, we could raise our eyes and see this brilliant starry road,
00:16but today, we are lucky when we can count the stars on the fingers of the hand.
00:21It has nothing to do with nature, it is simply due to the growing threat of what is called light pollution.
00:27The next time you walk around a big city at nightfall,
00:31take the time to note how many streetlights, neon billboards, and office buildings remain on all night.
00:39These urban lights create an artificial brightness that rivals the natural light of the stars.
00:45This is what is called light pollution, and it keeps getting worse.
00:50Every year, the Earth increases its brightness by 10%.
00:54This means that a person who is now born in a region where you can see about 250 stars,
01:00will only be able to see about a hundred at the age of 18.
01:07Unfortunately, this problem already occurs in large cities, where observing the stars is only done in planetariums.
01:13So much so that, during an earthquake that deprived Los Angeles of electricity in the 90s,
01:19many residents called the emergency centers to report the presence of a huge silver cloud in the night sky.
01:25What they actually saw, perhaps for the first time, was the Milky Way.
01:31When you look at the Earth from space, you can see the vast regions of North America,
01:36Europe, the Middle East, and Asia all illuminated.
01:40Singapore, Qatar, and Kuwait are among the countries most polluted by light.
01:46Conversely, remote places like Siberia, the Sahara, and the Amazon rainforest are plunged into total darkness.
01:54Light pollution manifests itself in several forms.
01:57First of all, there is dazzling.
01:59For example, when you drive and all these bright lights literally hurt your eyes.
02:04It's very unpleasant.
02:05Then, there is accumulation, like in Times Square, with all these bright lights scattered all over the place.
02:11Light intrusion is when the light penetrates subtly into places where it should not be,
02:17like a reverberator in your bedroom.
02:20Finally, there is overexposure, which consists of using far too much artificial light for no valid reason,
02:26like when offices remain lit all night when there is no one.
02:30And all these forms of light pollution are not content to steal the beauty of the night sky from us.
02:35It also disturbs astronomical studies.
02:38When we rely too much on artificial lights, the work of terrestrial telescopes is disturbed.
02:43And when these equipment cannot do their job properly,
02:47we need even more expensive space telescopes, like Hubble and James Webb.
02:52And let's be honest, we're talking about billions of euros.
02:55The transformation of night into day concerns all of us, and not just astronomers.
02:59Night light disturbs our sleep schedules and the internal clock of our body.
03:04This clock controls brain activity, hormone levels, and cellular functions.
03:09When it is disturbed, it can lead to serious problems such as depression, insomnia, heart problems, or even worse.
03:17One of the key processes that is disturbed is the production of melatonin, a hormone that appears at nightfall.
03:23Too much light at night lowers the rate of melatonin,
03:26which leads to stress, anxiety, headaches, and lack of sleep.
03:31Blue light is particularly harmful in this regard.
03:34You may think that just turning on night mode on your phone screen is enough, but you are wrong.
03:40Blue light is also present in LED bulbs,
03:43the ones we use at home and in urban lighting because they are cheap and save energy.
03:49What I mean is that blue light is omnipresent and that it is very difficult to avoid it completely.
03:56This is also largely the reason why we are not quite sure of the extent of light pollution today.
04:02Some statistics suggest that this problem increased by 49% in 25 years, until 2017.
04:09But the real figure could be even higher.
04:12The fact is that blue light has shorter wavelengths,
04:15and the satellites we rely on today struggle to detect it with precision.
04:19This means that they do not realize the extent of the light pollution caused by LED bulbs.
04:26Animals are also lost and disoriented.
04:29Are their sleeping habits also affected?
04:32A German study has revealed that the marmots in urban areas become active much earlier than those in natural habitats.
04:38They wake up and start singing about five hours earlier than their country cousins.
04:43Migratory behaviors are disturbed,
04:46especially among birds such as swallows and cranes that move at night.
04:51You can imagine how disoriented they are when they see something like the Las Vegas sphere,
04:58lit by one or two million LED bulbs.
05:01The intense brightness hides the stars and disturbs their migration over thousands of kilometers and continents.
05:08And that's not all.
05:09Artificial lighting is also the cause of the increase in the number of birds
05:14that crash into skyscrapers and high-rise buildings.
05:18Insects, especially mosquitoes, are also affected by light pollution.
05:22Yes, they are a little disgusting.
05:24And it may not bother you that they are attracted to artificial lights,
05:28and that they suffer their fate.
05:31But don't forget that they are an essential source of food for many animals,
05:35such as bats or frogs.
05:37And that a disturbance of their population could disrupt entire food chains.
05:43Night lights also cause problems underwater.
05:46Marine creatures that live near luminous panels off the coast of the Galician coast
05:51modify their behavior.
05:53And there is less and less acidity and sea anemones in these illuminated areas.
05:58Another example concerns sea turtles.
06:01They usually lay their eggs on beaches and often return to the same place for years.
06:06But when these beaches are too illuminated at night,
06:09female turtles can be disoriented and decide not to lay their eggs there anymore.
06:16Do we really need all this light?
06:18Difficult to say.
06:20Some people think it's safer that way.
06:22But not everyone agrees.
06:24You see, it is usually the dazzling light that disturbs our vision.
06:28Here is an example.
06:29A powerful lighthouse blocks your view near a portal.
06:33And you see nothing but the light.
06:35But if you partially cover the light with your hands,
06:38you can suddenly spot an intruder.
06:40Wow!
06:41What I mean is that more light is not always synonymous with more security.
06:47It's about using it correctly.
06:49And the fact of reducing the intensity of the lighting can actually strengthen security.
06:54In addition, it can save you money.
06:57In this regard, the waste of light has a considerable impact on the economy.
07:01Take, for example, a classic lamp.
07:04The light it projects directly represents only 30% of the total light it emits.
07:09In the United States alone, about a third of the night light is wasted.
07:13This represents a staggering annual cost of 2.2 billion dollars.
07:19Electric lights are not only disadvantages, of course.
07:23They have brought us good things,
07:25such as the lengthening of our days,
07:27which allows us to do more things and have fun after work.
07:30But we can completely minimize this problem.
07:33Turning off all lights would be great,
07:35but let's be realistic.
07:37It's very difficult, if not impossible, nowadays.
07:40So, what can we do?
07:42Use sophisticated devices such as light variators,
07:46stopwatches and motion detectors
07:49to ensure that our lighting is ultra-efficient.
07:52Choose rather warm-colored lamps
07:54than too raw blue lights.
07:56And use closed-envelope lighting devices,
07:59like these beautiful old-fashioned table lamps.
08:02They direct the light downwards,
08:04where you need it and avoid being dazzled
08:07and lighting up what is not meant to be.
08:09In addition, by reducing the waste of light,
08:11you are not only helping the planet,
08:13you are also saving money on your electricity bill.
08:16Everyone wins.
Comments