Astronomers are concerned that street-lighting changes in Palmerston North will mean more light pollution that will interfere with stargazing.
Lights that throw illumination upwards, as well as shining down on the road, mean it is harder to see the sky, said former president of the Palmerston North Astronomical Society Ian Cooper.
He said astronomers were concerned about the use of LED lights for street lighting.
"While they are cheaper to run, they can't be screened out with filters [in telescopes] the way the old sodium lights, around most of the streets, could be.
"The thing about LED lights, they are cheaper to run, but they are hard on the eyes and give a glare and glow that can't be screened out."
But Cooper acknowledged that in the end, the public saw this as a roading and safety issue.
The cost of bulbs and of operating lighting drove any decision, rather than considerations for the impact on astronomy.
Palmerston North City Council project engineer Rob Cuff said there was likely to be a changeover to LED lights.
He said LEDs were being trialled now in Cascade Cres, Kensington Mews, Vivian St and Wharite Place in Palmerston North as well as Hillary Cres in Ashhurst.
Cuff said a business case would go to the city council recommending changing 6500 lights to LEDs, which used about 59 per cent less power than the orange sodium lights.
"And there is less maintenance replacing them. An orange bulb lasts about two years, and LEDs about 12 years."
Cuff said astronomers should welcome the LEDs as they would all point down to the road, with little light escaping upwards and blocking out views.
The council hoped to share the costs of changing lights with the NZ Transport Agency and he thought the changeover could start in June next year.
Cuff said moving to LEDs was a no-brainer, as they were cheaper to run and could be installed easily.
He said the plan was to change all subsidiary roads, such as residential streets and cul de sacs over to LEDs, while leaving sodium lighting on the major routes such as Fitzherbert Ave, Rangitikei St and Broadway.
He said it was more expensive to change big sodium lights used on major roads.
Cooper said photos had been taken from Wharite Peak in 1996, 1998 and in the past week, and the last one showed more light pollution from the city.
For the past two years the Horowhenua Astronomical Society has raised similar concerns with the Horowhenua District Council through submissions to its draft Annual Plan.
This year Horowhenua agreed to work with the society to discuss lighting options.
- Manawatu Standard
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