The widespread use of artificial light at night means we're seeing a 10% decrease each year in the number of visible stars in the sky
Our ability to see the stars in the night sky is eroding very quickly due to the widespread use of artificial light at night. Prof Brian Espey, Associate Professor of Physics at TCD and chairman of Dark Sky Ireland joined the Drivetime show on RTÉ Radio 1 to talk about this issue. (This piece includes excerpts from the conversation which have been edited for length and clarity - you can hear the discussion in full above).
While we are seeing a 10% decrease each year in the number of stars which are visible, Espey says "the amount of light we see from satellites is not increasing at the same rate. It looks like the impact may be due to the increasing use of LEDs, which tend to produce light that's a little bit bluer than the light we've been used to and it's quite a strong effect."
He believes it's something we need to be aware of for numerous reasons. "I think we're realising more and more that we need to find a way of actually working in favour of nature. We have got two great parks here, one at Dark Sky Reserve in Kerry and one at Dark Sky Park in Mayo, and there are a number of other areas which are equally good, and we could actually protect and this will also bring in tourists.
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From RTÉ Radio 1's News At One, astronomers warn view of night sky is under threat
"It's something that rural development people are recognising. It's a resource that we can easily lose by just over lighting. We lose our access to the sky, but we also lose the ability to actually attract people here, maybe on the back of ecotourism, and also being able to see pristine sky, that you can see in Europe, for instance."
One issue which Espey addresses is that of lighting streets for health, safety and security. "The lighting we tend to use now has a little bit more blue richness to it and that is not so good for our night vision. If you've seen new lights in your area, you'll probably say 'they're much brighter than the old lights' and they have an influence on the vision that's normally active at night.
"What we've been doing in Dark Sky Ireland is supporting the use of warmer white lighting. If you go to buy a light in the shop, it'll be listed as warm white, it'll have colour temperatures, we say, about 2700 Kelvin or 3000 Kelvin. It's a lot easier on our eye and it's a lot less damaging to the environment. Since we have an aging population, less blue light is easier for older eyes as they start to get cataracts, so it's less glare as well. It reproduces colour better, so it's better all round."
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From RTÉ Radio 1's Nature Nights, founder of Visit Dark Skies Etta Dannemann talks about the fundamental importance of our relationship with the night sky
"It's not that we want to get rid of light, it's we like light done right," says Espey. "We've seen, for instance in the United Kingdom, they've reduced the amount of light -- under the old lighting system, the lights were put in at a certain level for the maximum amount of traffic on that road. And it was very hard to change the level. Now, with LED technology, we can dim the lights or we can turn them off at hours, for instance, down the country, when there's really no noticeable traffic, without having an impact on safety or collisions.
Dark Sky Ireland has received funding from the Heritage Council to pursue this for Newport, Co. Mayo and make it a Dark Sky town. "We've started this project with reducing the level of light on the church, which also has the benefit then we can actually see the Harry Clarke windows much better than you could under the old system", explains Epsey.
"It shows it's possible to get buy-in from the community and actually tick all these boxes, and save energy, and have better lighting. I think councils are seeing that this is a potential win-win-win situation across the board."
