It made perfect sense. Where there are people there’s light, and therefore where there’s light, you can never truly be away from people or their influences. But there’s also light where there are only people some of the time: roads, warehouses, industry, infrastructure. Subtle though it is, understanding this relationship between human-manufactured light and the night sky will lead you to the emptiest parts of Britain.
During idle moments over the next few weeks I learned some interesting things about light pollution. I learned that light that falls away from the area where it’s needed or wanted is called ‘stray light’ and an unwanted invasion of this – be it a washed-out night sky with stars lost to the amber haze of a nearby town or the clumsily angled floodlight on your neighbours’ wall that lights up your bedroom like an atomic flash every time a cat walks under it – is given the apt term ‘light trespass’. Lighting used to throw dramatic illumination on a building or object is called ‘accent lighting’, and I also learned that all of these are in general bad news to lovers of dark skies and given the neat collective term ‘night blight’. One of the worst-afflicted places on the planet is Tsim Sha Tsui in Hong Kong, where the level of light has over 1,200 times the value defined as the international standard for a dark sky.* The facility where this is measured is, with unfortunate irony, the Space Museum. I also learned – thanks to a charming organisation called the International Dark Sky Association – that an unspoiled sky is visually packed with stars right down to the horizon and the starlight is strong enough to cast noticeable shadows on land. In such conditions, picking out individual constellations is almost impossible to the untrained eye given their sheer abundance above.
I also learned that, perhaps surprisingly, Britain has some of the largest areas of dark sky in Europe. This was illustrated by a natty map of the United Kingdom as if seen from space, with clumps of heat-signature colour spread over the country like an outbreak of digital pox. The largest population centres – London, Liverpool and Manchester, Birmingham and Glasgow – were coloured an angry red, surrounded by a scab of yellow, gradually fading into pale blue. The areas of least pollution were deep navy, tonally seamless with the sea. On land, the places where these were darkest and most extensive were the mountains. Scotland blended with the sea just north of Stirling. The Pennines, the Southern Uplands of Scotland, the moors of the south-west, and the Lake District were all dark – as were blanket swathes of Wales.
The population-density maps had been one thing, but I hadn’t seen anything quite so starkly illustrative of this idea of mountain ranges as islands – or voids – amidst British civilisation. This map cut through the intricate camouflage of daylight, highlighting human intrusion like phosphorescence in a murky lake: a true map of British space. And a week into May, with my eye on the weather I picked the best of a bad bunch of moonless days and headed for South Wales, to spend the night on top of the mountain – all being well – that lay beneath some of the darkest, most spacious skies on the continent.
The mountains of the Brecon Beacons – like most British mountains – are totally unique. The name rather evocatively comes from the signal fires once lit on their summits to warn of approaching English raiders. But whilst many other mountains wear the suffix of ‘Beacon’ across the land, none is quite like the Beacons of Brecon. None is even a bit like them.
Such is the ancient, much-brutalised geology of the British Isles, that every bit of land sticking its neck up has been battered by a particular something, in a particular manner, at a particular point on its long journey, marking it as different to mountains not that distant from it. That’s why British mountains have long been of interest to geologists: they are some of the most scrawled-on and kicked-about creations nature has ever sculpted, and they wear these signatures like scars.
The Beacons are a perfect case in point. From a distance, as you approach from the direction of south-west England, their character is clearly seen. They look like they’ve been finely carved from wood by a carpenter with an eye for nautical lines; all elegant scoops, gorgeously concave faces and wedged prows, a natural symmetry that seems somehow too symmetrical to be natural. These ingredients rise, gently but inexorably steepening towards the 900-metre contour line, whereupon they are abruptly sliced flat, as if by plane and spirit level. Their characteristic form is best demonstrated by the highest massif – the ‘Brecon Beacons’ themselves, the central trio of Pen y Fan, Cribyn and Corn Du – but all of these startling mountains display the same touch. The other visible hallmark is their cladding: these are not cragged and hard-skinned like the mountains of Glen Coe or Torridon, or even Snowdonia. All have coats of horizontally ridged green corduroy, the edges of which catch the first winter snows and hold the last, striping the mountains white. Where paths have worn through, the mountains beneath bleed sandstone a vivid, Martian red. The flat ‘billiard’ tops exhibited by the most distinctive of these mountains are the remnants of ‘plateau beds’ – a much grittier, harder sedimentary layer that has been chewed into the air by weathering, then resisted further attack. If the mountains look as if they’ve been cut flat it’s because, in a manner of speaking, they have.
These central mountains are the most frequently climbed of the Brecon Beacons, and are rewarding and accessible to all. The drops are huge, the views immense, the sense of achievement fulfilling and the aesthetic tremendous. But it wasn’t Pen y Fan I was here to climb. At each of the park’s extremes lie two ranges that confusingly share the promising (promising if you’re in search of a lovely dark night sky, anyway) name of Black Mountain. Well, they almost share it: the Welsh names for each reveal the subtlety lost in their English translation. One lies close to the English border in the east, and is a high but inauspicious collection of moorland summits bearing the collective name the Black Mountains (Y Mynyddoedd Duon). The other, on the park’s spacious western fringes, bears the singular denotation the Black Mountain (Mynydd Du), and this one most definitely earns its chops in the spectacle stakes. Burly and remote, its summits are in fact the hoisted edges of an enormous, wedge-shaped escarpment, tilted into the ocean of moorland like a sinking liner.
The more specific names associated with this mountain and its features are rather bewildering, and you may have to bear with me here. Mountain toponymy – as we will continue to see anon – is not an exact science, and is often inconsistent across a relatively short distance. A summit in South Wales (Fan, Ban, Bannau, Pen) isn’t necessarily a summit in North Wales (Carnedd, Moel), although in both places a llyn does tend to be a lake, cwm a valley, craig a crag, bwlch a pass, and fach and fawr little and large, respectively. The Black Mountain as a massif is Mynydd Du; the long escarpment of the eastern flank is given the name Fan Hir, fan meaning crest. But fan can also mean peak – and there are two of these on the Black Mountain, three if you count Bannau Sir Gaer, which uses the term bannau, which is probably derived from ban, which is in turn the plural of fan. Bannau Sir Gaer means the ‘Carmarthenshire Beacon’, and this is often still known by its mixed translation Carmarthen Van, van being yet another variant of fan. Fan Foel is one summit, probably meaning ‘bald peak’; Fan Brycheiniog is the other, named after the small kingdom to which the mountain belonged in the Middle Ages. Like I said, bewildering. But if you take anything from this, make it simply the following: mountain names can be complicated. And it was remote Fan Brycheiniog – at 802 metres the highest point of the Black Mountain – that was to be my mountain of space.
The weather was, it has to be said, not good at all. The rain held off long enough for me to enjoy the sinuous roads over the border and the tentatively awakening villages and pubs as I approached Brecon. It even stayed clear enough to appreciate the tall, distinctively clipped top of Pen y Fan as I passed Brecon and headed for the empty western part of the national park. A few miles outside a little place called Trecastle, a left turn led into a long valley of