One of Sydney's most recognisable lighthouses will be home to the first officially recognised city-based stargazing zone in the Southern Hemisphere.
Palm Beach headland, which boasts the Barrenjoey Lighthouse, has been marked as an Urban Night Sky Place by the global body DarkSky International.
The official listing recognises the area for its darkness in an urban environment where light pollution obstructs views of the night sky.
In 2018, Northern Beaches local Marnie Ogg proposed to Northern Beaches Council to have the headland recognised as an Urban Dark Sky Place.
She says the area stands out for being so close to the city while being surrounded by large national parks and the sea.
"It is not within the sky glow of Sydney at all," said Ms Ogg, who is the director of outreach for the Australasian Dark Sky Alliance.
"You've got very little population, you've got national parks and the sea around it which produces this lovely dark sky spot."
The DarkSky organisation now recognises 10 locations as Urban Night Sky Places, most of which are in the Midwest and South-west United States.
Among the list is Saguaro National Park in Tucson, Arizona, Minamirokuroshi in Japan, and a park in Sherbrooke, Canada.
Ms Ogg says the Sydney location just 30 kilometres north of Sydney's CBD is unique for being close to a major city.
"I think it is exceptionally unusual," Ms Ogg said.
"Cities obviously just add light and add light.
"To have a city destination that is still so dark, I think you could almost say it's a one in a million."
A citizen science project that collected data over 12 years found that city light pollution was increasing around 10 per cent per year.
Northern Beaches Mayor Sue Heins said it is important to protect the ability to see the stars as cities expand and light pollution increases.
"This designation is a testament to our commitment to preserving and celebrating the beauty of the night sky amidst urban environments," Cr Heins said.
Council devised the application with the support of Ausgrid and National Parks and Wildlife Services.
Vigorous qualification process
To become recognised by the Arizona-based DarkSky International, the area has to be proven to be dark enough.
This involves providing photographic evidence and demonstrating that the lights in the area are up to stargazing standard.
Ms Ogg said that includes making sure night-time lights are not pointed upwards.
"You write a plan to say, 'this is how we're going to use our lights' so that we know that we're keeping the night time sky as beautiful as possible," Ms Ogg said.