00:00Eight people out of ten in the world can no longer see the Void Lactée.
00:03And in a hundred years only, it could not be a forgotten story.
00:07It's not the galaxy that disappears, but the cosmos that separates.
00:11At the time of our grandparents, we could raise our eyes and see this cloud cloud cloud,
00:16but today, we are lucky when we can count the stars on the hands of the hand.
00:21It has nothing to do with nature.
00:23It's simply due to the massive threat of what we call the luminous pollution.
00:27The next time you walk into a big city in the night,
00:31take the time to notice how many lamps of air,
00:33the newspaper panneaux publicitaires in neon,
00:35and walls of bureaus rest allumés all night.
00:39These urban lights create an artificial luminous light
00:42which rivalizes with the natural light of stars.
00:44It's what we call the luminous pollution.
00:47And it doesn't cease to grow.
00:50Every year, the Earth increases its luminousness of 10%.
00:53This means that a person who is today in a region where we can see about 250 stars
00:59can see only one hundred stars arrive at the age of 18 years.
01:07Malheureusement, this problem is already in the big cities,
01:10where the stars are not only in the planetariums.
01:13At the point that, during a earthquake of Earth
01:15which has deprived Los Angeles of electricity in the 1990s,
01:19many inhabitants have called the emergency centers
01:21to signify the presence of an enormous green light in the dark sky.
01:25What they saw in reality, maybe for the first time,
01:28it was the Milky Way.
01:30When you look at Earth from space,
01:33you can see the vast areas of North America,
01:36Europe, the Middle East and Asie all illuminated.
01:40Singapour, Qatar and Kuwait
01:42figure out among the most polluted countries by light.
01:46In the other hand,
01:47places like the Siberia, the Sahara and the Amazonian forest
01:50are plunged into the most total darkness.
01:54The luminous pollution is manifested in several forms.
01:57First of all, there is an explosion.
01:59For example, when you drive
02:00and all these lights are alive
02:02they are literally bad at the eye.
02:04It's very nice.
02:05Then, there is the accumulation,
02:07like at Times Square,
02:08with all these bright lights
02:10painted a little everywhere.
02:11The intrusion of light,
02:13when the light penetrates
02:14in the places where it should not be found,
02:17like that of a reverb in your bedroom.
02:19Finally, there is the surillumination,
02:22which means to use too much
02:24too much artificial light
02:25without reason available,
02:26like when the bureaus
02:27remain allumés all night
02:29while there is no one.
02:30And all these forms of luminous pollution
02:32do not feel like
02:33the beauty of the night sky.
02:35They also perturbate
02:36the astronomical studies.
02:38When we depend too much
02:39artificial light,
02:40the work of the Earth's telescope
02:42is disturbed.
02:43And when these equipment
02:44do not work correctly,
02:46we need space telescopes
02:48even more expensive,
02:49like Hubble and James Webb.
02:51And honestly,
02:53we are talking about
02:53millions of euros.
02:55The transformation of the night
02:56in the day
02:56concerns all of us
02:58and not only astronomers.
02:59The dark light
03:00disturbs our sleep
03:01and the internal clock
03:03of our body.
03:04This clock controls
03:05the cerebral activity,
03:06the levels of hormones
03:07and the cellular functions.
03:09When it is disturbed,
03:10this can cause
03:11serious problems
03:12such as depression,
03:14insomnia,
03:15cardiac problems
03:16or worse.
03:17One of the key processes
03:18which is perturbated
03:19is the production of
03:20melatonine,
03:21a hormone
03:22which appears
03:22at the night.
03:23Too much of light
03:24does increase the amount
03:25of melatonine,
03:26which leads to stress,
03:28anxiety,
03:29pain and sleep.
03:31The blue light
03:31is particularly
03:32negative at this point.
03:34You might think
03:35that it is enough
03:35to activate the mode
03:36night on the screen
03:37of your phone,
03:38but you are wrong.
03:40The blue light
03:41is also present
03:42in the LED ampoules
03:43that we use at home
03:45and in the urban light
03:46because they are
03:47good market
03:47and economic energy.
03:49What I want to say
03:50is that the blue light
03:51is omnipresent
03:52and that it is very
03:53difficult to avoid
03:54completely.
03:55It is also
03:56in large part
03:57the reason why
03:57we are not sure
03:59of the height
04:00of the light pollution
04:01today.
04:02Some statistics
04:03suggest
04:03that this problem
04:04has increased
04:05from 49%
04:06in 25 years
04:07until 2017.
04:09But the real number
04:09could be even higher.
04:11The reality
04:12is that the blue light
04:13has longer
04:13longer than
04:14longer.
04:15And the satellites
04:15that we depend on today
04:17peine to detect it
04:18with precision.
04:19This means
04:19they do not account
04:20all the measure
04:21of the light pollution
04:22caused by the
04:23electromagnetic lights.
04:26The animals
04:27are also lost
04:27and disorientated.
04:29Their sleep habits
04:30are also affected.
04:32A German study
04:32revealed
04:33that the birds
04:34of the urban areas
04:35are activated
04:35much earlier
04:36than the natural habitat.
04:38They wake up
04:39and start singing
04:40about five hours
04:41more than their
04:41cousins of the camp.
04:43The migrations
04:44are disturbed
04:45in particular
04:46for the birds
04:47like the birds
04:48and the birds
04:49who move out
04:50at night.
04:51You can imagine
04:52how much they are
04:53disorientated
04:54when they see
04:55something like
04:56the sphere
04:57of Las Vegas
04:57lighted by
04:591 or 2 millions
05:00of light bulbs
05:00light.
05:01The intense light
05:02hide the stars
05:03and disturb their migration
05:05on thousands
05:06of kilometers
05:06and continents.
05:07And this
05:08is not all.
05:09The light light
05:10is also
05:11as the origin
05:12of the increase
05:13of the number of
05:14animals
05:14on the ground
05:15and the walls
05:16of large height.
05:18The insects,
05:19including the
05:19moustiques,
05:20are also affected
05:21by the luminous pollution.
05:22Yes, they are a bit
05:24of a bit
05:24and it may not be
05:25that they may be
05:26attracted by the
05:27light bulbs
05:28and they,
05:28they,
05:29they are
05:30their sorts.
05:30But don't forget
05:31they are a source
05:33of essential food
05:34for many animals
05:35like the
05:35dinosaurs
05:36or the
05:36animals
05:37and that a perturbation
05:38of their population
05:39could hurt their
05:40entire chains.
05:43The darkness
05:44cause also
05:45problems
05:46under the water.
05:46The marine creatures
05:47living near the
05:49light bulbs
05:49large
05:50of the
05:50coast
05:50and there are
05:53more and less
05:54acidity
05:55and anemones
05:55of the sea
05:56in these areas
05:57of the sea.
05:58Another example
05:59concerning the
05:59tortoise
06:00of the sea.
06:01They usually
06:01pond their
06:02oeufs
06:03on the beach
06:03and they often
06:04come to the same
06:05place for years.
06:06But when they are
06:07too dark
06:08the night
06:08the tortoise
06:09female
06:10can be
06:10disorientated
06:11and they decide
06:12to no longer
06:13their oeufs.
06:16Have we really
06:17need this light?
06:18Some people think
06:21that it is more
06:21sure.
06:22But everyone
06:23does not agree.
06:24You see
06:25that it is generally
06:25the eblouissement
06:26that perturbe
06:27our view.
06:28Here's an example.
06:30A powerful lamp
06:30can block your view
06:32near the door
06:33and you see nothing
06:34other than the light.
06:35But if you
06:36cover partially
06:37the light with your hands
06:38you can suddenly
06:39see an intrude.
06:40Wow!
06:42I mean
06:42that
06:43more light
06:44is not always
06:45synonym
06:45to more security.
06:47It is
06:48to use it correctly.
06:49And
06:50the fact
06:50to reduce
06:51the intensity
06:51of the light
06:52can actually
06:53strengthen
06:54the security.
06:55In addition,
06:56it can make you
06:56save money.
06:58In this regard,
06:59the burning of light
06:59has a considerable impact
07:01on the economy.
07:02For example,
07:03a classic lamp.
07:04The light that it directly
07:05represents
07:06only 30%
07:07of the total light
07:08that it is emitted.
07:09In the United States,
07:11about a third
07:11of the dark light
07:12is gaspillée.
07:13It represents
07:14an annual cost
07:14of 2,2 milliards
07:16of dollars.
07:19The electric lights
07:20are not only
07:21any inconvenience,
07:22of course.
07:23They have given us
07:23good things,
07:24such as the length
07:25of our days,
07:26which allows us to do
07:27more things
07:28and to enjoy
07:29after work.
07:30But we can all
07:31minimize this problem.
07:32To open all the lights
07:33would be formidable.
07:35But let's realize,
07:36it is very difficult,
07:37even impossible,
07:39of our days.
07:40So,
07:40what can we do?
07:42We can use
07:42sophisticated devices
07:43such as
07:44light bulbs
07:45for Beatletter
07:47light bulbs
07:48that we start
07:49with accurate lights.
07:55using black lights
07:57lights
07:57use a black light
07:58as지는
08:01light lighter
08:03that you have to
08:05want
08:05to avoidอยu
08:06sterilizer point you
08:10don't
08:10neue you have to
08:12spend the light
08:13you also spend money on your electricity bill.
08:16Everyone wins.
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