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Old 17 December 2010, 11:11   #1
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How far is the Horizon?

A commonly asked question on RIBnet.

So I thought I would share a handy tool I'd found on the Internet for working out the horizon from any height.

http://www.boatsafe.com/tools/horizon.htm
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Old 17 December 2010, 12:08   #2
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Superb

I was talking to Erin about this, not in a nautical sense but wondering if it was possible the see the light pollution of the South Coast from a plane over Alderney.
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Old 17 December 2010, 13:03   #3
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WOW, suprised it is such a short distance you can see, knew it wasnt that far but didnt realise it was soo short.
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Old 17 December 2010, 13:10   #4
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Well its shorter than I thought, Ive always been using a 5 mile rule due to the curvature of the earth
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Old 17 December 2010, 13:19   #5
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Quote:
Originally Posted by malthouse View Post

I was talking to Erin about this, not in a nautical sense but wondering if it was possible the see the light pollution of the South Coast from a plane over Alderney.
Interesting. Assuming I was at about 1,000 ft in the plane when I saw the glow, the horizon is some 42 statute miles away according to the website. Supposing the lights on the south coast of England are 100 or 200 ft above the horizon, and given my fantastic eyesight , I suppose there is a very slight possibility that I did see the glow radiating from all those wasteful street lights. I guess there might be some diffraction involved which may be 'bending' the light waves over the surface of the sea as well.
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Old 17 December 2010, 13:46   #6
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I've long been fascinated by how far you can see from Jersey. For instance, from my bathroom window (about 380ft asl) I can easily see Cap Frehel and Pointe du Grouin (both 40 miles away). Years ago, there was some discussion in the Jersey Evening Post as to whether it was possible to see Mont St. Michel from the Island. The received wisdom in those days was that, at 48 miles, it was too far away. Actually MSt.M is visible and on some days it can even be quite clear. The problem is knowing where to look as it lies behind the Chausey Archipelago and so can easily be missed. It's not a naked eye object and even with binoculars you can't see it all; normally only the spire is visible, although this autumn I did manage to resolve some of the land below as a clear triangular mass. I was going to take a photo with my cousin's 12" telescope but never got round to it.

As to being able to see the UK from above Alderney, I would say it would be quite easy under the right conditions. I've seen both at the same time on several occasions when flying above mid Channel.
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Old 17 December 2010, 15:02   #7
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View from Jersey

GJOKYZ, your bathroom is 380ft above sea level ?? Which parish is that in ??

The new Air Traffic Tower is 374ft above sea level and the view is amazing . Les Platons Radar is 330ft above sea level.

Mont St Michel was visible from the old tower but the view from the new building will be far better on the right day. The twin spires at Coutainville were clear to see last week.

I will have to organise a RIB.net visit when Martin is over from Alderney if anyone else is interested ??

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Old 17 December 2010, 15:11   #8
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Well its shorter than I thought, Ive always been using a 5 mile rule due to the curvature of the earth
It's not really. It's a bit abstract and I guess refers to the actual zero height horizon. Try entering 0.1 feet as the viewing height

5 Miles would be about right for a normal wheelhouse height view of another small craft.

Divers will be familiar with the restricted horizon experienced on the surface.

I'm having fun entering the viewing heights of certain ribnetters. Obviously, Lord "Chuck Norris" Vetinari can see OVER the horizon but others have to buy yellow ribs so they can spot 'em from the bank....
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Old 17 December 2010, 15:12   #9
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GJOKYZ, your bathroom is 380ft above sea level ??
The new Air Traffic Tower is 374ft above sea level and the view is amazing .
Oops, he'll have to fit curtains
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Old 17 December 2010, 15:26   #10
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GJOKYZ, your bathroom is 380ft above sea level ?? Which parish is that in ??

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Is that right? I always thought the highest point was 460ft asl; where did I get that from I wonder? In that case, my house must be about 280ft asl as it's at Coin Motier in St. Lawrence. I'm sure I saw the height of the adjacent field on the Digimap at work as being 360ft asl; I must have misread. I would love to see the new tower by the way; count me in for a visit.
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