maandag 21 april 2014

Secrets Of Legendary Viking Crystal Sunstones And The Mysterious Uunartoq Artifact Unraveled - In ancient times, the Vikings explored strange new lands and visited many distant places located across the ocean. While voyaging on the seas, how did the Vikings know where they were going?
There are several ways Vikings navigated. One method for navigating was to observe migrating animals. Another way was to observe the stars.
The Norse sagas also mention a mysterious "sunstone" used for navigation.
One of the reasons why the existences of sunstones have long been disputed is because they are contained in the saga of Saint Olaf, a tale with many magical elements.
However, this has changed and now. Sunstones can no longer be considered just a myth.
Archaeologists have discovered a special crystal that suggests legendary Viking sunstones did exists in reality.

The crystal uncovered in the 1592 sunken Elizabethan shipwreck near the Channel Islands, between England and France is shown to be an Iceland spar.

The research team headed by scientists at the University of Rennes says the stone was next to a pair of navigation dividers, suggesting it may have been kept with the ship's other navigational tools.It is believed that Vikings used so-called sunstones as a compass to find their way in arctic waters. Researchers suggest that sunstones could have been held up toward the center of the sky, allowing sunlight to hit it and get polarized and broken into an "ordinary" and an "extraordinary" beam.

On a clear not cloudy day, they could have rotated the crystal until the pair of beams lined up. By noting where the sun was when this happened, navigators could make a reference point to use even when the Sun was obscured by clouds or twilight.
If the crystal is held east-west, the double image becomes a single image and thus allows a sailor to locate the Sun.

This crystal found at the Alderney shipwreck. Image credit & copyright: Alderney Museum

According to the study published in the journal Proceedings of the Royal Society A."such a crystal immersed in sea water play a crucial role by limiting the solubility, strengthening the mechanical properties of the calcite, while the sand abrasion alters the crystal by inducing roughness of its surface.
Although both phenomena have reduced the transparency of the Alderney calcite crystal, we demonstrate that Alderney-like crystals could really have been used as an accurate optical sun compass as an aid to ancient navigation, when the Sun was hidden by clouds or below the horizon.
To avoid the possibility of large magnetic errors, not understood before 1600, an optical compass could have helped in providing the sailors with an absolute reference. An Alderney-like crystal permits the observer to follow the azimuth of the Sun, far below the horizon," the research team writes in the science paper.

As highly skilled navigators, Vikings crossed thousands of kilometres of open sea.
Credit: Bryba Prods/united Artists/The Kobal Collections

It is doubtful archaeologists will ever uncover a complete crystal in a Viking site because Vikings preferred to commit their dead to funeral pyres, cremating them and their grave goods.
Then there is the mysterious Uunartoq artifact that could shed more light on how Vikings navigated 1,000 years ago. The disc is estimated to have been about seven centimeters in diameter.
Researchers based at Eötvös Loránd University in Hungary have studied the Uunartoq artifact that was discovered in an 11th century convent in Greenland in 1948.

Click on image to enlarge
The Uunartoq disc. Credit: Proceedings of the Royal Society 

When the artifact was discovered some dismissed it as simply a decorative object. Other scientists believe that the Uunartoq disc was used as a compass by the Vikings as they traversed the North Atlantic Ocean from Norway to Greenland.

"Vikings routinely crossed the North Atlantic without a magnetic compass and left their mark on lands as far away as Greenland, Newfoundland and Baffin Island.

Based on an eleventh-century dial fragment artefact, found at Uunartoq in Greenland, it is widely accepted that they sailed along chosen latitudes using primitive Sun compasses. Such instruments were tested on sea and proved to be efficient hand-held navigation tools, but the dimensions and incisions of the Uunartoq find are far from optimal in this role.

On the basis of the sagas mentioning sunstones, incompatible hypotheses were formed for Viking solar navigation procedures and primitive skylight polarimetry with dichroic or birefringent crystals," a team of Hungarian researchers wrote in their science paper.

A closer examination of the Uunaritoq artifact reveals that disc could in fact have functioned as a single entity. However, it is more likely the disc was used in conjunction with other tools - including a pair of crystals and a flat, wooden slab - to help navigate when the sun was low in the sky or even below the horizon.
"When the sun is low above the horizon, even the shadow of a small item can fall off the board, and such situations are frequent in the northern seas," said study co-author Balázs Bernáth.
With help of the crystal sunstones, the Vikings could locate the sun after sunset. Such crystal calcite stones produce patterns when they're exposed to the polarization of UV rays within sunlight.
This means that when the crystals are held up to the sky, the orientation of these patterns cast within the stone can help pinpoint the position of the sun below the horizon. Once the Vikings had determined the position of the hidden sun, they could have used a specially designed wooden slab called a shadow stick to simulate the shadow of the gnomon based on the angle at which the hidden sun would hit it. The location of the outer edge of that imaginary shadow could then have been used to determine their cardinal direction.
The discovery of the crystal sunstone and the Uunartoq artifact provides us with valuable knowledge how the Vikings could navigate long distances so many years ago.

The Viking ships were silent, swift, and light enough to be pulled ashore
and carried over land.

The Norse saga tells:
"The weather was very cloudy. It was snowing. Holy Olaf the king sent out somebody to look around, but there was no clear point in the sky. Then he asked Sigurd to tell him where the sun was. After Sigurd complied, he grabbed a sunstone, looked at the sky and saw from where the light came, from which he guessed the position of the invisible sun. It turned out that Sigurd was right."
For a long time, this intriguing story baffled historians. Today, we know the mythical Viking sunstone was a polarizing crystal that was most likely used by the Vikings to successfully navigate across the North Atlantic to the New World.


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