We lived in Wellington, New Zealand for more than 20 years, and I was able, from time to time, to stargaze from the back garden. My view of the sky was restricted by trees and hills, but the sky was pretty starry on suitable nights.
I can pick out a number of constellations and have pointed out the Southern Cross and other features to various friends and visitors over the years.
Then one year we visited Tonga on holiday. We stayed at the wonderful Ha’atafu Beach Resort with its half dozen fales on the beach. Late one night after dinner we walked away from the fales down to the beach and gazed with astonishment at the stars. The sky was so full of such bright stars I actually couldn’t pick out any of my favourites. It was utterly breathtaking.
Now we live at our own beach house around 90 minutes drive north of Wellington. Our view of the sky is unrestricted.
The sky here is way darker than it was in Wellington: I can see the Large and Small Clouds of Magellan without difficulty, for example. It’s definitely not as dark as it was in Tonga though, and to the south, southeast and north I can see the glare of the lights of Otaki, Masterton and Levin.
I count myself very privileged to have such a wonderful view of the night skies, but worry about ever increasing levels of light, especially as more people build around here.
That’s a worry shared by many people around the world, some of whom apparently can’t even see the dark sky any more because of all the spilled light.
An article in Science Advances, The new world atlas of artificial night sky brightness, says:
[The new world atlas of artificial night sky brightness] shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world’s land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights.
Just look at this world map from the article. [BTW: I fixed it to put New Zealand in its rightful place at the centre.]
Most of the northern hemisphere suffers from a huge amount of light pollution, as does most of South America. The rest of the southern hemisphere has its problem spots, but is fairly to very dark.
In New Zealand Auckland is a problem, as is Christchurch, though to a lesser extent. Wellington isn’t great, but it’s not too bad either.
When you zoom in on the original map of New Zealand in the article there are some mystery bright spots off Taranaki (West Coast, North Island). I suspect those are offshore oil and gas fields:
Other sources of differences between prediction and actual measurements may be as follows: snow coverage, different outdoor lighting habits (for example, effective laws against light pollution), the presence of atypical lights (for example, greenhouse lighting, fishing lights, and gas flares), curfew, the presence of temporary lights detected by satellites that are no longer active, and vice versa.
Light can be very damaging. Quite apart from spoiling the night sky, the birthright of everyone on this planet, it can disrupt our sleep, damage the life cycles of other creatures and simply waste energy and increase other forms of pollution.
While polluted rivers, oceans, land and air are very hard to fix — how do you get the toxins out again? — fixing light pollution is comparatively easy. After all, if you flick a switch, the lights go out and the sky is dark.
We need lights for our modern civilisation, but perhaps, surely, we don’t need as much or as many.
Everyone could be more careful about lights:
- point lights down to the area where light is needed
- shield lights to stop them from spilling light to areas where it’s wasted
- turn off lights that aren’t needed
- reduce the amount of light to only what’s necessary.
There are phrases in English about being
kept in the dark (a bad thing) or
shining a light on something (a good thing). When those phrases refer to knowledge and information that’s fine. But when it comes to our good health and the good health of the planet their connotations reverse: we need the dark. A dark sky is a good sky, at night, at least.
Oh, and if you haven’t glanced up at the night sky recently step outside and take a look while you can still see some stars. They’re something of an endangered species.
BTW: see also my post The long and short of it in which I explain how to read one of the graphs in the article quoted above.