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Often regard as remorseless robbers , the Vikings were also telling old salt open of traversing the North Atlantic along a well-nigh straight line . Now , new interpretations of a knightly reach suggest the sea robbers may have skillfully used the sunlight to operate the compass even when the sun had localise below the horizon .
The stiff of the theorize compass — known as theUunartoq disc — were found in Greenland in 1948 in an 11th - century convent . Though some researcher originally argued it was simply a ornamental object , other investigator have hint the disc was an authoritative navigational tool that theVikingswould have used in their roughly 1,600 - mile - long ( 2,500 kilometre ) trek from Norway to Greenland .
The Uunartoq disc was discovered in an 11th century convent in Greenland in 1948. It is thought to have been used as a compass by the Vikings as they traversed the North Atlantic Ocean from Norway to Greenland.
Though only one-half of the wooden disk remains , it is estimated to have been approximately 2.8 column inch ( 7 centimeters ) in diameter with a now - lose central pin that would have cast a tail from the Sunday indicative of a primal way . [ Images : Viking Twilight Compass Helps Navigate North Atlantic ]
Researchers ground at Eötvös Loránd University in Hungary have studied the fragment in item . They close that although the disc could have functioned as a individual entity , it was more probably used in conjunction with other puppet — include apair of crystalsand a insipid , wooden slab — to help pilot when the sun was modest in the sky or even below the horizon .
" When the sunshine is low above the horizon , even the phantasm of a lowly detail can fall off the panel , and such situations are frequent in the northerly ocean , " said study co - author Balázs Bernáth .
Researchers say this crystal found at the Alderney shipwreck near the Channel Islands could prove fabled Viking sunstones really did exist.
Bernáth and fellow worker recall that , to help solve this foresighted - phantasm job , the Vikings may have used a low - lying , domed object in the middle of the compass to create a wide , shorter shadow than a moretypical sundial spikewould . A wide hole within the nerve centre of the disk — previously interpreted as a place to fascinate the compass — could have served as a holding spot for this so - called central gnomon , the team suggests .
The researchers think that , to locate the sunshine after sunset , the Vikings could have used apair of crystals known as aventurine , which are calcite stones that bring about patterns when they ’re exposed to the polarisation of ultraviolet rays within sunlight . When the crystal are held up to the sky , the predilection of these patterns cast within the stone can help oneself pinpoint the position of the sun below the purview .
Once the Vikings had determine the position of the hidden sun , they could have used a specially contrive wooden slab call a shadow reefer to simulate the shadow of the gnomon based on the angle at which the hidden sun would hit it . The locating of the outer edge of that imaginary phantasma could then have been used to determine their key direction .
The researchers conducted field tests to forecast the plausible accuracy of this so - called fall compass , and find that it would have bring with only 4 degrees of error , which is good than other forms ofcelestial navigationand like to modern magnetic pouch compass , Bernath enounce .
" Not the safe , maybe , but it would have been a really freehanded help , " Bernath told Live Science .
The team estimated that the twilight compass would have functioned for as long as 50 minute after sundown around thespring equinoctial point , when the Vikings are thought to have used this compass based on etchings in the Ellen Price Wood .
No shadow stick or aventurine have been find in colligation with the saucer , but grounds of both live in medieval drop a line record book , suggest they would have been available to the Vikings .
Related : How Do Compasses Tell Which direction Is North at the South Pole ?
The team said the finding are a testament to the sophistication of this group of people often remember as gentile .
" They were unpitying robber , but not only ruthless robber , " Bernath said . " This instrument is quite remarkable . "
The study finding are detail today ( March 25 ) in the journal Proceedings of the Royal Society A.
