Light pollution
Let me remind you today about the problem of the light pollution of the night sky. It is a problem of our time, development of cities and civilizations. The lamp's light makes it difficult to observe the night sky and has a negative effect on the life of animals and plants adapted to live in the dark during the night. It probably also has a bad effect on human health.
Mosaic from the night satellite images of the Earth depicting the scale of light pollution, as well as population density.
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The night satellite image of the Earth shows the scale of the problem. Areas with high population density are clearly visible. The main cause of the problem is street and advertising lighting, lighting of architectural objects such as churches and lighting of sports arenas. It is estimated that 70% of people in the world live in areas contaminated with light. In urban areas the sky is never darker than on a moonlit night outside the city. Such conditions make it virtually impossible to see stars in cities, and seeing the milk route is impossible. To a large extent, the high level of illumination of the sky is responsible for the poor construction of street lamps, which should mainly illuminate the streets. The worst kind of street lamps are so-called glass balls that shine in every direction. If the lamp luminaires were properly made, the sky lighting could be reduced by up to 30%, and replacing the traditional sodium lamps (glowing in yellow) with LED directional lighting would improve this effect even from 50%. Unfortunately, in the modern world it isn't possible to completely remove the night lighting, you can only contribute to its reduction and increase energy savings.
Comparison of the night sky view from the rural area (at the top) and the urban area (bottom). Light pollution reduces the visibility of the stars.
I remember when I was little, in the summer I watched a beautiful milk road even 20 km from a big city. In the 90s in Poland there were many places without lighting. Only Warsaw and the Silesian agglomeration were the dominant sources of lighting. In 2010, the situation was much worse. Now in Poland only the Bieszczady mountains have a truly dark night sky. In order to protect the best places, two dark sky protection parks were set up here: Park of the Star Sky "Bieszczady" and the Izerski Park of the Dark Sky in the Sudeten Mountains. In these places, the construction of any lighting is controlled.
My private picture : Cracow by night
Finally, let me remind you about the influence of each of us on this problem. If people were more economical and didn't give in to fashion for lighting the facade of their homes, the problem could be a bit smaller. On the other hand, lighting is a symbol of night security, which is why most people will not agree to give up night lighting. And what do you think about this?
Greetings to lovers of Astronomy!
Sources:
Light pollution
Ecological light pollution
Lighting
and my knowledge...
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The growth of light pollution has been staggering in the past few decades. Somewhere there is a link that shows this growth. I remember from my teens from where I lived that the skies were quite dark. In the same area the skies look permanently lit like a full moon.
You are totally right Terry, I also remember in the mid to end 90th was the sky a lot darker.
A few years ago the lights were turned off when the people were sleeping (When I remember right it was from 22:00 to 5:00). Nowadays and thanks to the invention of LED the streetlights will shine the whole night. Due to the fact that they need a lot less power, it is not necessary to turn them off.
My neighbors also light their garden with a 5,000 watt (not really, but it feels so) LED spotlight the most of the whole night. I can even see my shadow when I'm in the garden and this beast is turned on.
See how the situation in Poland changed. As a child in the 90s, I also remember very dark nights and a bright milky way through the whole sky.