One of New Zealand’s most respected astronomers is petitioning the Government to introduce light-cutting legislation to preserve our globally-important “dark skies”.

University of Canterbury Emeritus Professor John Hearnshaw wants New Zealand to adopt similar laws as those recently passed in France, where businesses are now required to shut off illuminated signs and displays between 1am and 6am.

His petition, backed by the country’s official astronomy body, comes amid growing efforts to create new dark sky reserves across Aotearoa: most recently in South Wairarapa and Carterton.

Artificial light at night - or ALAN – is an increasing environmental problem, posing large and widespread impacts on a multitude of species that depend on natural dark.

In our largest city, researchers have found Auckland’s bright lights are likely hurting local ecosystems, while partly masking the lunar cycle and ruining residents’ view of the Milky Way.

Last October, a University of Auckland study reported how light pollution had caused hundreds of seabirds to crash into city buildings – including a dozen that hit the Sky Tower.

Globally, the problem has been shown to change the timing of dawn song in birds, stymie the nocturnal movement of small mammals and fatally attract phototaxic insect species to light.

University of Canterbury astronomer Emeritus Professor John Hearnshaw. Photo / Supplied

For people, disruptions to our circadian rhythm increased risk of sleep disorders, obesity and depression.

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Further, Hearnshaw said cutting pollution – particularly from poorly-installed outdoor lighting that burned through electricity and projected light upward – could save money and energy.

“More than a third of light at present is actually being wasted, and that’s costing New Zealand millions of dollars each year,” Hearnshaw said.

“This isn’t about having complete darkness or anything like that – we still need light at night for safety – but just being very careful about where it’s shining.”

He proposed a national law that would set new controls on outdoor lighting, such as 10pm curfews for illuminated advertising signs, limits on what street lights could emit, and reductions in blue light across cities and towns.

Searchlights and lasers should be banned or strictly controlled, he said, while floodlighting of buildings should be curtailed and also subject to curfew.

For commercial office buildings and shop windows, lights could be switched off after 10pm – or windows should be screened with opaque blinds or curtains, which he also recommended to cut light pollution from homes.

He and others had been lobbying councils through the Dark Sky Network NZ, but with limited success.

“We’ve been giving the same advice over and over to lots of councils – so I think there’s a need to be more efficient and have one national law, rather than lots of ordinances at council level.”

Royal Astronomical Society of New Zealand (RSANZ) president Nalayini Brito supported the appeal for a new law, which she said would offer more protection for some two-dozen aspiring and existing dark sky places in the country.

“I think that to preserve our dark skies for future generations, you have to control lighting – and it has to be legally enforceable.”

Brito also serves as a director of the International Dark Sky Association, which this month certified the Wairarapa Dark Sky Reserve amid just 20 other places worldwide.

Among astronomers, she said New Zealand remained one of the most important star-gazing locations on the planet.

Light pollution in Auckland has been causing harm to species like seabirds. Photo / Mark Mitchell

That wasn’t just because of our view to unique celestial features, but the relative abundance of dark skies over the country.

Just over half of New Zealand’s land area enjoyed pristine night skies, and the Milky Way was visible from over 96 per cent of the land area.

Currently, about three quarters of the North Island and 93 per cent of the South Island still experienced only low levels of light pollution.

Globally, the picture was grimly different: one major new study published this month estimated light pollution was increasing by 10 per cent each year, rather than two per cent in line with population growth as earlier thought.

The RASNZ was now running a nationwide campaign to create an up-to-date baseline for New Zealand and is recruiting Kiwis to observe levels in their own areas next month, with a Facebook live event scheduled for February 17.

Hearnshaw also noted the cultural importance of Matariki – now a national holiday – along with the economic benefits of “astrotourism”, particularly in places like the Mackenzie District.

As well as promoting his petition, he was preparing a submission to the Natural and Built Environment Bill – the principal replacement of the soon-to-be-scrapped Resource Management Act.

His call has already drawn support from other astronomers, including the University of Auckland’s Professor Richard Easther.

“This is a great initiative,” Easther said.

“The night sky is part of our shared heritage as human beings, and minimising the unnecessary impact of artificial light on the environment makes sense — culturally, environmentally and economically.

“There is a fair bit of detail to get right, but it should be a win for everyone.”

Environment Minister David Parker has been approached for comment.