The horizon… it hunts the human eye, inspires the imagination, and energises exploration – each feeding our obsession to know ‘what lies beyond‘?
Each morning – come rain, come shine – my first outward gaze is drawn to the horizon. What will today bring? … a golden sunrise? … a rumpled sea? … smooth sets marching from the edge of the world? … a passing ship? … the threat of rain? And, for the avid photographers of Lorne … another dawn to surpass all dawns before?
How many of our days now begin with a Facebook or Instagram check – and another sunrise from Lorne’s intrepid early-risers: Keith Miller at sea, Rainer Reinbold at the Swing Bridge, Ian Walding on the pier, or Judi Kenneally on a pre-dawn stroll.
The horizon has tempted – and taunted – man since time began.
“An infinite horizon is like a strong current in the sea; it drags you to unknown places before you even notice it!”
― Mehmet Murat ildan [a ‘horizon-besotted’ contemporary Turkish thinker]
Many are those who have been drawn to seek the edge of the world. The Vikings struck west into the setting sun to find new worlds – Iceland, Greenland, Canada, and the Americas; then, centuries later, Magellan, Columbus, Vespucci, Cabot, and Pizarro would seek spice, gold, and conquest – while dragging disease, devastation, and the destruction of priceless civilisations in their wake.
The horizon … the thin line that demarcates the intersect between sea and sky – a ‘touch’ point known as ‘the offing’ … is in constant change. In but moment, it can change from a line as sharply defined as the edge of a razor to a smudge so soft, so blurred that the human eye blends sea with sky, and sky with sea, and there is no telling where one is lost or the other gained. Clear air before rain and the image sharpens, a drifting drizzle or a sea mist and the image dulls.
Here, in Lorne, we are blessed by the sight of both sun and moon as, due east, they rise over the edge of the world. The full moon sheds a silver path of light fit to walk upon, while a dawning sun colours the horizon in every shade of red, purple, orange. Of an evening, as the waning sun sets behind the dense forests of our Otway hinterland, its dying rays flame the cloud-banks of the far horizon in a cloak of the palest pink and blue, and in fires of crimson. No wonder that horizon photos jostle each other, cheek and jowl, among the daily photo posts on the One and Only Lorne Community Facebook Page.
But my own horizonal interests are piqued by mathematics. I have always been intrigued by ships that, edging slowly across the offing, sit proudly ‘on the line’ when viewed from the tide line, but that lie well within the sea’s perimeter when simultaneously viewed from the Country Club! Clearly, the distance to the horizon must be quantified by the viewers’ height above sea level … but how – and by how much? Paraphrasing https://en.wikipedia.org/wiki/Horizon “… the higher the eyes above sea level, the farther away the horizon“.
If we make three assumptions: [1] there is no atmospheric effect – though as the atmosphere bends – or ‘refracts’ – light, this assumption will always be slightly incorrect: [2] the earth is a sphere – though this is also not quite true despite that the difference is minor: [3] the earth has a known radius of 6,371 kilometres … then the distance to the horizon [in kilometres] = √ 13 x the height [in metres] of the observing eye above sea level 1. Alternatively, you can use a simple calculator from the Internet 2.
- 4.7 km for someone 1.70 m tall standing at sea level.
- 5.1 km distant for someone 2.0 m tall standing at sea level.
- 19.6 km away when 30 m above sea level [Lorne Hotel deck].
- 35.7 km distant from a hill 100 m above sea level [Big Hill].
- 102.8 km away if standing atop the 828 m Burj Khalifa in Dubai.
- 336.1 km from the 8,848 m crest of Mt Everest.
I decided to run an experiment. I waited for a ship! Obligingly, one soon pottered along past the pier – one of those ubiquitous ‘block-of-flats-on-the-horizon’ shapes that modern ships have sadly now become … gone is the romance of a ‘proper’ ship shape!
First, using the Marine Traffic and My Altitude apps on my iPhone, I drove to the Golf Club carpark [Altitude: 129.84 m; Horizon: 40.7 km] for Photo #1, then hot-footed it to the rocks at the bottom of the North Lorne Beach access stair [Altitude: 3.2 m; Horizon: ~6.5 km] for Photo #2 … time between the two photos = 4.5 minutes. The relationship between the passing ship and the horizon at both sites is shown in the accompanying two photos.
Importantly, I had lots of fun doing it … and what better way to occupy a few minutes near the closing of the day!
Photo #1 [Lorne Golf Club Car Park]
Photo #2 [North Lorne Beach
References:
- https://www.wikihow.com/Calculate-the-Distance-to-the-Horizon?amp=1
- Distance to the Horizon Calculator: http://www.ringbell.co.uk/info/hdist.htm
John Agar
