Old shool navigation redscovered -- again

[MN Dave]

https://arstechnica.com/science/2018...y-have-worked/

“The weather was thick and snowy as Sigurður had predicted. Then the king summoned Sigurður and Dagur (Rauðúlfur's sons) to him. The king made people look out and they could nowhere see a clear sky. Then he asked Sigurður to tell where the Sun was at that time. He gave a clear assertion. Then the king made them fetch the solar stone and held it up and saw where light radiated from the stone and thus directly verified Sigurður's prediction.”

http://www.nordskip.com/iolite.html

iolite1.jpgiolite2.jpg
https://www.ksl.com/?sid=27804704

A Viking sunstone is actually what we now know as cordierite. Cordierite is a crystal composed of magnesium, iron and aluminum that has a unique property that the Vikings found very useful — it can detect the direction from which polarized light is coming.

Light scattered by air molecules is polarized and the direction of polarization is at a right angle to the sun. A cordierite crystal is translucent yellow, but due to its crystalline structure the stone turns a blue and purple color when it is turned at right angles to the sun, even when the sun is obscured by clouds.

https://www.polarization.com/viking/viking.html

https://greenzaku.deviantart.com/art/Iolite-changing-color-143766672

The upper and lower pictures are of the SAME STONE, a drilled bead, pictured at different angles under exactly the same lighting conditions. This fascinating change of colour that occurs when the stone is viewed at different angles is known as ' pleochroism ' and is caused by the 'double of refraction of light of a mineral.

[Nicholas Scheuer]

Re: Old shool navigation redscovered -- again

fascinating!

[George Ray]

Re: Old shool navigation redscovered -- again

The old becomes new again.

[willin woodworks]

Re: Old shool navigation redscovered -- again

Thats too cool

[skaraborgcraft]

Re: Old shool navigation redscovered -- again

I say Benson, be a good chap and pass up the Garmin.....

I wonder how accurately it can pin point, surely that would come down to the fineness of each stone to filter? I wonder when the concept of "do we have enough time" or "not enough time today for that" started, outside of referring to sun and moon or day and night? Would vikings and their Sagas have spoken to times past in a different way? Hey Argen, whats the time? "It is 3 suns into the day after the snow melt, in the Reign of Vlad the Impaler......."

[MN Dave]

Re: Old shool navigation redscovered -- again

I say Benson, be a good chap and pass up the Garmin.....

I wonder how accurately it can pin point, surely that would come down to the fineness of each stone to filter? I wonder when the concept of "do we have enough time" or "not enough time today for that" started, outside of referring to sun and moon or day and night? Would vikings and their Sagas have spoken to times past in a different way? Hey Argen, whats the time? "It is 3 suns into the day after the snow melt, in the Reign of Vlad the Impaler......."

<< Sigh, nobody ever reads my links>> In the first link, they said accurate within a few degrees.
Another source says

Researchers say Vikings used transparent calcite crystal to fix the bearing of the Sun, to within a single degree of accuracy.

https://phys.org/news/2011-11-viking-sunstone-myth.html

Massive coronal mass ejections usually miss us, but if one makes a direct hit, the Garmin will be fried. For rad hard instrumentation I would recommend a sextant over the sunstone. Remember Carrington flare of 1859? Another flare in 1877 set fires in telegraph offices.

[skaraborgcraft]

Re: Old shool navigation redscovered -- again

My bad, i had a Benson moment before reading your link! My plastic sextant is never far away.....i remember the panic in the early days when the system was shut down or severely degraded, and overheard a distraught yachtie complaining he would have to learn Astro......

[Small boats rock]

Re: Old shool navigation redscovered -- again

Navigation doesn't matter so much with an ultra shoal draft boat designed for running up on the beach or bouncing over a reef. Put the stone away and hand up another beer

[Hugh MacD]

Re: Old shool navigation redscovered -- again

I would recommend a sextant over the sunstone. .

I think the sunstone was only used when visibility was so poor that sun/stars couldn't be seen. It wasn't a "pinpoint navigation" tool, but it'd getcha pointed the right way. Mostly according to the sagas they seem to have navigated by sun, stars and wave patterns.