Sunstones and Viking ‘magic’

Intriguing navigational aids of the ancient Icelandic seafarers



Many centuries before there were navigation charts or compasses, ancient mariners may have been able to determine the position of the sun in a clouded sky to within a degree or so of its actual position.1 This fascinating ‘know-how’ seems likely to have been utilized up to a millennium or so ago before being lost to subsequent generations. The story involves the legendary Vikings—not the first time we have reported on the seafaring abilities of ancient Nordic and Icelandic peoples.2

Before the days of satellite-navigation systems, ships’ captains and sailors in general needed tools to help pin-point the position of their vessel; major errors in plotting a course could have fatal consequences. This involved determining both the latitude and the longitude as accurately as possible. Longitude is notoriously difficult without accurate timepieces. However, as long as the sun was visible, latitude3 could be determined quite accurately—but what to do in rough weather or when the sun was obscured for days on end? New research, published in the prestigious Proceedings of the Royal Society A, suggests that the Vikings could have used a large crystal of calcite4 to locate the sun’s position indirectly.5 Calcite has long been called ‘Iceland spar’ (Icelandic silfurberg or ‘silver-rock’). But this recent research suggests that this was also the fabled Viking sólarsteinn (= ‘sunstone’).

As sailors on the high seas, making journeys of hundreds of miles in often dangerous waters, the Vikings would undoubtedly have relied on other clues too—thought to have included the stars, the motions of the waves, and even the behaviour of various sea-birds.6 However, the use of ‘crystal power’ is certainly intriguing. While the latest research was seized on by various news outlets worldwide, with headlines such as “Magical Viking stone may be real,”7 the principles have been discussed for some years, most notably in a well-researched book on Viking navigation, by the late Leif Karlsen.8

An experienced sailor and navigator himself, Karlsen presented an excellent case for transparent calcite being the Vikings’ sunstone, aiding them in determining the sun’s position.9

The research team responsible for the recent paper has formally demonstrated what Karlsen himself showed in his book. By exploiting the property of birefringence of a transparent calcite crystal, the Vikings could have located the sun in the sky. Even in twilight conditions, with the sun below the horizon, the paper claims, it could give them an absolute reference point. Birefringence simply means that a beam of light passed through such a crystal will be refracted into two beams, resulting in a double image. Iceland spar is an optical calcite, the angle of whose sides leads to this double refraction of light. Unlike direct sunlight, reflected light is polarized (with light waves in a particular orientation),10 true of the scattered light on a cloudy day. It’s thought that the Vikings exploited these properties of light by mounting a calcite crystal in a wooden block and rotating it horizontally until the brightness of the two images equalized,11 at which point they could determine the sun’s position accurately.

So, do we have any hard evidence that these legendary people navigated in this way? Although an Iceland spar crystal has been found on an Elizabethan shipwreck,7 archaeologists have found none associated with Viking wrecks or settlements. However, considering the fact that the Viking Sagas mention prized sunstones being used to navigate perilous Arctic seas, it seems very likely. This is further supported by what we know of their prowess and abilities generally. Also, the Bible informs us that people were made perfectly in God’s image (Gen. 1:26, 31), and that this image was broken but not lost at the Fall.12 So humans were endowed with intellect from the beginning of human history.

The technological ‘know-how’ in a given society generally increases over the generations. This is due to the fact that discoveries are made, and the knowledge transmitted to later generations, who can build on them with more discoveries. Research, such as that on these sunstones, increasingly points to impressive feats of human ingenuity long before the modern scientific era. This gives the lie to evolutionary ideas of human progress by defying the ‘chronological snobbery’ that goes with it.13

References and notes

  1. A degree is about two sun diameters in the sky, however. Return to text.
  2. Catchpoole, D., Ancient mariners had current knowledge, Creation 29(4):54–55, 2007; Return to text.
  3. In this context, latitude is the angular distance from the equator (north or south). It is measured in degrees along the meridian of a model globe or map; the equator is 0° and the poles are 90°. Return to text.
  4. A form of calcium carbonate (CaCO3). Return to text.
  5. Ropars, G. et al., A depolarizer as a possible precise sunstone for Viking navigation by polarized skylight, Proc. R. Soc. A 468(2139):671–684, 2011. Return to text.
  6. See, accessed 22 February 2012. Return to text.
  7. The Daily Telegraph (UK),, 2 November 2011. Return to text.
  8. Karlsen, L.F., Secrets of the Viking Navigators: How the Vikings used their amazing sunstones and other techniques to cross the open ocean, One Earth Press, 2003. Return to text.
  9. For Leif Karlsen’s excellent summary of the technique of using calcite as a navigational aid, see, accessed 22 February 2012. Return to text.
  10. You can see this with polaroid sunglasses, designed to block the polarization of reflective glare. Return to text.
  11. Technically, the point of rotation which equalizes the intensity of the double image, with a birefringent crystal, is called the isotropy point; at which depolarization of the light occurs. Return to text.
  12. Cosner, L., Broken images, Creation 34(4):46–48, 2012. Return to text.
  13. Human ingenuity has if anything been declining, on average, since the Fall, as we continue to accumulate an increasing load of genetic defects. But as a word of caution on early technology, see Sarfati, J., Computers on the Ark? Creation 33(2):40–41, 2011; Return to text.

Helpful Resources

One Human Family
by Dr Carl Wieland
US $19.00
The Puzzle of Ancient Man
by Donald Chittick
US $15.00
Soft cover