NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
False Horizons
From: Mike L
Date: 2007 Nov 20, 03:43 -0800
From: Mike L
Date: 2007 Nov 20, 03:43 -0800
As a separate question to my other post, I want to use a sextant on land to demonstrate to children that you can locate your position with the sun. The obvious first problem is getting an accurate fix on the "horizon", and the obvious answer (even without a book) was to use a reflection. All good in theory, but in practice it is full of problems. 1. there is the problem of keeping a bowl of water still with kids jumping up and down, 2. trying to get children to stay one position long enough to keep the reflection in view 3. using the filters makes it even worse because they can't see the bowl of water and the sun's reflection is quite a bit darker. Eventually for my younger child I tried setting up a plank in the garden and tying the sextant up with string to give a level, but the darn sun moved so quick that it ran off the end before I had a chance to set it up with any accuracy. I'd appreciate any ideas! Refraction errors on false horizons The great advantage with a false horizon for children (as opposed to the sea), is that there is no need to pay for icecreams! AKA, taking the children to the sea side - but more importantly there is no need to know the size of the sun, the height of the waves, the height of the person or anything else like that as they all cancel out. The great disadvantage is that you still have refraction through the atmosphere (though not of the horizon!) and the only table I have doesn't list refraction of the horizon separately from that of the direct view of the sun so I would appreciate some information on this error! --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---