Southern African astronomy buffs have another reason to celebrate – hot on the heels of the awarding of the greater part of the Square Kilometre Array to the region, comes the news that the NamibRand Nature Reserve in Namibia has been proclaimed as the continent’s first international dark-sky reserve (IDSR), meaning that it’s one of the best places on earth to star-gaze.
The proclamation falls under the dark-sky movement, an initiative of the Arizona-based non-profit International Dark-Sky Association (IDA) which was the first organisation, and is currently the largest, to embrace this concept.
Located in southwestern Namibia, the privately owned NamibRand covers an area of just over 170 000 ha.
It joins a handful of other areas around the world – and only three other reserves, in New Zealand, Canada and the UK – recognised by the IDA as the best places on earth to see the splendour of the universe at night, just as it was before humans came along.
The dark-sky movement seeks to limit the intrusion of artificial light into the experience of observing the night skies. The adverse effect of this intrusion is known as light pollution, and it happens when artificial light is not properly shielded, causing sky glow, glare or light trespass. This limits the ability to see details of the night sky whether unaided or through a lens.
Light on the ground need not be unfriendly to dark skies, if properly set up. But poorly shielded artificial light, according to the IDA, also affects the ecology of an area and impacts on nocturnal animals, predatory behaviour, migration patterns and the mating and communication habits of creatures.
Gold tier status for dark-sky excellence
While not the first IDSR in the world, the NamibRand is the first to achieve gold tier status. For stargazers this is good news, because it means that the reserve is unparalleled in terms of night-time viewing as any artificial lights that are present make little or no impact on the dark sky. The nearest town lies over 100km away, and the closest major city is Windhoek, some 400km distant.
For ecologists, gold status is a sure indication that the NamibRand staff has made every effort to keep the impact of artificial light on the reserve’s fauna to a minimum.
"We did a detailed audit of all external light fixtures on the reserve and applied corrective measures, including retrofitting, replacing fixtures or using lower wattage bulbs," said the reserve's CEO Nils Odendaal, "so that these would comply with our lighting guidelines as stipulated in our dark-sky reserve management plan."
According to the reserve's dark-sky lighting guidelines, exterior lighting is kept to a minimum and where necessary, is not only fully shielded, but emits an amber or red light which is kinder to the eyes. Lights are also controlled by motion detectors or timers, where possible, to ensure they’re on for as short a time as possible.
Vehicles are encouraged to use headlights (on dim) only when the light of the moon is insufficient, otherwise they use parking lights. It’s perfectly safe to drive using these less powerful lights at the slower speeds used on the reserve. Headlights on bright are only allowed on the public road C27, and vehicle lights may not be directed at buildings or tourist accommodation.
The reserve will continue with its responsibility of raising awareness of the importance of preserving the night skies.
“NamibRand serves on several local and national committees where we can share information with other conservation organisations and stakeholders,” said Odendaal. ”An example of this is the recently launched Nam-place project, which aims to unite landowners and custodians across large landscapes in an effort to co-manage these local landscapes for the benefit of conservation.”
NamibRand is using its position on these committees, and its close ties to bodies such as the Namibia Nature Foundation, to drive awareness about light pollution and light conservation in general, said Odendaal.
In addition, the NGO Namib Desert Environmental Education Trust, located in the reserve, educates visitors, schoolchildren and neighbouring communities about astronomy, the night sky, and other aspects of conservation and sustainability. The organisation hosts about 1 000 school children each year and also disseminates environmental literature to a readership base of about 18 000 readers, said Odendaal.
Exceptionally dark skies
NamibRand’s application was submitted to the IDA in February 2012. It was championed by retired physics and astronomy professor George Tucker from Nassau, New York. Tucker is an IDA member who had first visited Namibia back in 2003 and, he said in the application’s introduction, was amazed at the sheer volume of stars visible to him there – stars he’d never seen before.
He was even able to move around, in the dark, by the light of the Milky Way alone.
Over the past eight years Tucker has been conducting measurements of the darkness of the Namibian sky, using a sky quality meter – this is an instrument which gives a measure of the night sky’s brightness in terms of the magnitude per square arc-second.
An arc-second is a unit of angular measurement that is equal to 1/3600 degrees of an arc – we understand that there are 360 degrees in a circle, 60 arc-minutes in a degree, and 60 arc-seconds in each arc-minute. The arc-second is a tiny measurement – for a human hair to cover one arc-second it would have to be viewed from 10 metres away.
The magnitude is simply a measure of the brightness of an object.
The higher the number given by the sky quality meter, the darker the sky. Tucker consistently got readings of over 22 on his meter – this means that observers will be able to see, with a help of a telescope, stars of the 22nd apparent magnitude, which are very dim. To put this in perspective, the faintest celestial object visible to a sharp naked eye is around magnitude six, and that’s in exceptionally dark conditions. The spiral galaxy M81 or Bode’s Galaxy, magnitude 6.9, is about 12-million light years away and pushes the ability of the naked eye to the limit.
In terms of the Bortle Dark-Sky Scale, which measures night skies on a scale from one to nine – where one is dark enough to observe phenomena such as zodiacal light and shadows cast on the ground by the Milky Way, and nine is a brilliantly lit urban sky – the NamibRand comes in at one.
The measurements haven’t changed in all of the eight years, wrote Tucker, and it was these outstanding readings that prompted him to nominate the NamibRand as an IDSR.
"Viewing the pristine night sky over the NamibRand is an unforgettable experience,” he said in a statement. “Achieving this status is a significant accomplishment not just for the NamibRand, but also for Namibia and all of Africa."
Because tourism forms the major part of the NamibRand’s income, it’s imperative for the sustainability of the reserve that its natural assets are protected. As an astrophotography site, it would be highly sought after.
The &Beyond hospitality group maintains an observatory, which boasts not only a Meade LX200R 12-inch telescope but also a full-time astronomer, at its luxury Sossusvlei Desert Lodge, situated in the NamibRand. The group also played an important role in the reserve’s new IDSR status.
Other concessionaires in the reserve include Wolwedans camp; the self-catering NamibRand Family Hideout; walking safari company Tok-Tokkie Trails; Namib Sky Balloon Safaris; and the conservation organisation N/a'an ku sê Foundation.
All of them have stated their commitment to the dark-sky project.
Keeping our night skies dark
According to Dark Skies Awareness, the natural sky brightness level for an unpolluted and clear starry sky is around 21.6 magnitude per square arc-second – at this level the Milky Way can be seen blazing overhead, as well as about 6 000 stars, with the naked eye.
Since viewers in bright cities may count themselves lucky to see a few hundred stars in the sky on a clear night, we begin to understand how important it is to maintain these dark-sky areas.
Not only are starry skies a pleasure to view, but they are an important part of human and natural life. Many animals only come out at night. Navigators have used, and still use the stars and constellations to guide them. Too much lighting leads to energy waste and the consequent release of greenhouse gases in the production of that energy. It’s even claimed that having better night vision will help to cut down on crime, as criminals will be easier to spot.
The IDA has named various measures people can take to keep light pollution to a minimum in areas where it matters. They include shielding outdoor lighting; using light only when necessary and then just enough to get the job done; using dimmers and timers; and using a red- or yellow-tinted light which isn’t as harsh.