2.6
Arctic night skies show effects of light pollution on nocturnal orientation

Did you know?
Herons, mallards, and indigo buntings etc use the night sky such as the north star to navigate.
Zooplankton use the moon for mass migrations.
Harbour seals use the stars to orientate themselves.
Rapid development in the Arctic is increasing light pollution.

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Light Pollution Experiment
Light pollution is the excessive and long-term use of artificial light. In cities, there is excessive light pollution, but this happens everywhere, even on empty roads with street lamps or in your home. In the Arctic, night-time lasts for several months of the year in winter and daytime lasts for many months (See story 6.5). There is less light pollution in the Arctic than elsewhere but we do not know if there is an effect of the big, new, industrial areas that have lights on all throughout the dark Arctic winter.
Photo: T. V. Callaghan
With the naked eye, humans should be able to see 2,500 stars on a clear night. But in the country side you may see only 200 and in the city, even fewer – only 10. More than one third of people on Earth cannot see the Milky Way, our own galaxy, with their naked eye. This number increases in Europe with 60% of people unable to see the Milky Way. This is due to excess light pollution all across the world.

Light pollution can have lots of dangerous impacts on wildlife all over the world. Many animals on Earth are nocturnal, meaning that they are active during night time and are more sensitive to daylight. Some examples of nocturnal animals are the leopard, owls, platypuses and hedgehogs.

For example, sea turtles will not lay their eggs and nest on beaches with lots of lights made by humans, which can harm their populations. If they do nest on light polluted beaches, the adult sea turtles and hatchlings can easily get disorientated and end up on roads or other unsafe areas whilst trying to find the ocean. Plants are impacted by excess artificial light too. The leaves on trees that are planted closer to light sources, such as a streetlight, will fall later in autumn than trees in more natural light conditions. This could impact a tree's pollination, fruiting and flowering schedules too, posing a threat for the wildlife that depend on it.
How many stars can you see?
How many stars can you see from your home? How many stars can you see in the city? What about in the country side or in a park surrounded by nature? Create a frame by using either cardboard, wood or paper. Cut out a 10cm x 10cm square frame from any material and use this to count the stars. Fill in the table below to compare how the light pollution varies among these different places by raising your homemade frame to the sky, and looking through it. Only count the stars within your frame. Bear in mind that it should be a clear night with no full moon in all the places you visit to see the stars, so check the forecast before you go!
As light pollution can be so harmful, it is incredibly important to try to prevent it in any way possible as you do not know who or what, it may be affecting. The best ways to prevent light pollution are to only use a light downwards and to close curtains when using lights inside.