light pollution from cities and satellites is making stars harder to see

This week, Aotearoa New Zealand officially celebrates Matariki for the fourth time, marked by the reappearance in the night sky of the star cluster also known as the Pleiades.

Yet, ironically, the accompanying celebrations and the legislation that declares Matariki a public holiday miss the mark. They fail to promote and protect the country’s dark skies, which are crucial to seeing the stars in this small constellation.

While the law recognises Matariki’s significance to Māori culture and heritage as the beginning of the Māori New Year, it does not acknowledge that it is predicated on the visual presence of the star cluster.

Even where Matariki is not visible owing to weather conditions, the ability to see other celestial markers is important (for example Puanga/Puaka, also known as Rigel). Light pollution is a visual barrier to experiencing these important stars.

Since the passage of the legislation, local councils across the country have marked the public holiday with various light displays. This year will be no different, with illuminated artworks, projections and lightboxes at Matariki festivals in several cities.

Tirama Mai (bringing the light) will return to Ōtautahi Christchurch with brightly lit displays. Tāmaki Makaurau Auckland will see some of its most popular sites, including Queen Street, lit up as part of Tūrama, a series of large-scale, illuminated art installations.

In Rotorua, Whakatū Nelson and Ōtepoti Dunedin, Matariki festivities include spectacular drone light shows which will light up the night sky.

After initially ignoring Māori advice that fireworks are not appropriate to celebrate Matariki, many local councils have now abandoned them. But festivities will no doubt continue to contribute to light pollution and ignore the need to protect dark skies at night.

These ill-conceived festivities are not surprising given the legislation fails to even mention dark skies. This is exacerbated by New Zealand emerging as a major player in the increasingly commercialised space sector which has developed rapidly since the first rocket lifted off from Mahia peninsula in 2017.

Fewer people can now see the Milky Way

Much of Aotearoa’s landmass has some of the darkest skies on the planet. Based on land area, 74% of the North Island and 93% of the South Island rest beneath night skies that are either pristine or degraded only near the horizon. Indeed, the area affected by direct illumination is very low.

Yet, intense urbanisation means only 3% of the population regularly experience such skies. About half of all New Zealanders can no longer see the Milky Way in winter.

Globally, the visibility of stars (an indicator of the level of light pollution) decreased by 7-10% per year from 2011 to 2022. The visibility of the night sky in New Zealand appears to be following a similar trend. Between 2012 and 2021, the area affected by light pollution grew at a rate of 4.2% above the global average.

Advertising and tourism campaigns reinforce the perception that Aotearoa has dark skies, but visible satellites could soon outnumber the stars people can see, from New Zealand and worldwide.

No legal protection of dark skies

At present, there is no explicit domestic law protecting dark skies, nor any international laws. The law declaring Matariki a public holiday missed an important opportunity to provide such protection.

To address this issue, a petition was presented to parliament in January 2023 calling for national legislation to promote and protect dark skies. In March this year, parliament responded it would not take further actions “due to other priorities on the government’s resource management reform work programme”.

This is not surprising. Nevertheless, we call on the government to develop legislation for the governance of dark skies in Aotearoa New Zealand that incorporates mātauranga Māori (Māori knowledge).

While there are a variety of ways this could be achieved, controlling light pollution is the crux of the issue. Light pollution emanates both from unmitigated urban lighting as well as the expansion of satellite constellations, which is steadily forming a global net of moving points of light in space.

An incremental approach could be a government-backed education programme to raise awareness of light pollution, followed by the development of a national policy for its control. An amendment to the Matariki public holiday law could then follow in recognition of the national interest.

We are aware the challenges ahead are many. Yet, protecting dark skies is vital from a Māori perspective. Practically, such protections are crucial to the enjoyment and honouring of Matariki as we continue to risk disconnection from one of our most important natural features.