Scientists Think They Have Found The Mythical ‘Sunstone’ Vikings Used To Navigate Warships 29

An oblong crystal found in the wreck of a 16th-century English warship is a sunstone, a near-mythical navigational aid said to have been used by Viking mariners, researchers said on Wednesday.

The stone is made of Iceland spar, a transparent, naturally-occurring calcite crystal that polarizes light and can get a bearing on the Sun, they said.

It was found in the remains of a ship that had been dispatched to France in 1592 by Queen Elizabeth I as a precaution against a second Spanish Armada but foundered off the island of Alderney, in the Channel.

British and French scientists have long argued that the find is a sunstone — a device that fractures the light, enabling seafarers to locate the Sun even when it is behind clouds or has dipped below the horizon.

Sunstones, according to a theory first aired 45 years ago, helped the great Norse mariners to navigate their way to Iceland and even perhaps as far as North America during the Viking heyday of 900-1200 AD, way before the magnetic compass was introduced in Europe in the 13th century.


But there is only a sketchy reference in ancient Norse literature to a “solarsteinn,” which means the idea has remained frustratingly without solid proof.

In a study published in the British journal Proceedings of the Royal Society A, investigators carried out a chemical analysis on a tiny sample, using a device called a spectrometer, which confirmed that the stone was a calcite.

The stone is about the size of a small bar of soap whose edges have been trimmed at an angle. In technical terms, its shape is rhombohedral.

It is milky white in appearance, and not transparent, but the new experiments show that this is surface discolouration, caused by centuries of immersion in sea water and abrasion by sand, the study said.

Using a transparent crystal similar to the original, the scientists were able to follow the track of the setting Sun in poor light, with an accuracy of one degree. In a second experiment, they were able to locate the Sun for 40 minutes after sunset.

Other factors provide evidence that this is a sunstone, according to the investigation, led by Guy Ropars of the University of Rennes, in France’s western region of Brittany.

The crystal was found in the wreckage alongside a pair of navigation dividers. And tests that placed a magnetic compass next to one of the iron cannons excavated from the ship found that the needle swung wildly, by as much as 100 degrees.

Put together, these suggest the sunstone may have been kept as a backup to a magnetic compass.

“Although easy to use, the magnetic compass was not always reliable in the 16th century, as most of the magnetic phenomena were not understood,” says the study.

“As the magnetic compass on a ship can be perturbed for various reasons, the optical compass giving an absolute reference may be used when the Sun is hidden.”

The authors also note previous research that some species of migrating birds appear to have used polarized light from the sky as a navigational aid or to recalibrate their magnetic compass around sunrise and sunset.

How does the sunstone work?

If you put a dot on top of the crystal and look at it from below, two dots appear, because the light is “depolarised” and fractured along different axes.

You then rotate the crystal until the two points have exactly the same intensity or darkness.

“At that angle, the upward-facing surface of the crystal indicates the direction of the Sun,” Ropars told AFP in an interview in 2011, when preliminary research about the Alderney stone was published.
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Read More : The Optics of Calcite

Not just the stuff of legend: Famed Viking ‘sunstone’ did exist, believe scientists

29 thoughts on “Scientists Think They Have Found The Mythical ‘Sunstone’ Vikings Used To Navigate Warships

  • Randy patterson

    I hope the article’s author is continuing to study up on science terms, like “theory” and “refracted”. The cannon mentioned had some magnetic content, apparently. Was it in the article to provide an example of why a compass wouldn’t always be reliable? Why even bother mentioning any of it? Yeah, we’ve all heard speculation about how birds may navigate. Therefore, why not include a discourse on how light is polarized, and explain what it means? There could be a treatise on how many degrees of arc the sun travels per minute, too, and one could then go on to explain the term “nautical twilight”. Okay, sorry for the mild sarcasm. It’s a lot to digest before one ever gets around to discussing the topic of the story, you think? The readers may have instead wished for a bit more info regarding how such a crystal is made, and for more clarity regarding its use. Please try harder to stay on point in the future….

  • quakergirl

    If they could locate the sun 40 minutes after the sunset, that is more evidence that the earth is indeed flat and not spherical. The sun doesn’t set, it recedes out of view as in all perspective situations.

    • Randy patterson

      This is where the reporter left off by not further explaining the way light is refracted by the atmosphere, and how it becomes polarized by reflecting off layers in the atmosphere and from a body of water in particular. Yes, the sun recedes out of view at sunset, below the horizon, yet we still have a fair amount of working daylight, thanks to earth’s atmosphere. The source of that light is still by far the most intense when facing the direction of the sun. The earth is round again.

  • Helen Stark

    Wow… I have one of these!!! A few years ago, a retiring renowned fossil hunter/collector was selling his collection at the local rock club, and sold me one of these, along with some incredible specimens of other fossils. My piece is exactly 1 1/2″ x 13/16″ ground into a precise (to the eye anyway) parallelogram. There are no right angles, but it’s very uniform, and clear.
    He said he found it at a dig as is and called it icelandic spar. After I bought it as a mineral sample, I took it home and held it up to the light, and the rainbows that broke inside split near the lower 1/4 of the stone along a perfect line. I thought it was either a terrible cut (why not cut it so the internal rainbow was centered??), or had to serve a special function, but I had no clue what it could be. Anyone studying this phenomenon/function, please contact me on facebook, I may have one of the original working viking navigation stones.

  • Scott Templeman

    At least it isn’t skull-shaped. What a relief 😛 Let’s just hope there will not be an “Indiana Jones and the Viking Sunstone”

  • Jonathon Purnell

    Omg this crystal can be used for ahh, some FAR better applications in today’s world lol. It’s not just an arch find, it’s a means of real connective Faster-Than-Light communication, as stated in Bell’s Theorem.

    • TotallyRandomName

      You can’t just string together words you’ve heard and pretend you said something meaningful. It’s essentially a polarizing lens, it’s not doing anything magical that we haven’t been able to do before we found this.

      • Mew_Two

        I second that @TotallyRandomName:disqus I was thinking the same damn thing. Does this guy not know how prevalent calcite is.

        • Jonathon Purnell

          Well, perhaps you can enlighten me then 🙂 I had read that shooting photons into a calcite crystal would result in the photon being duplicated, in essence creating another photon (photon B) that shares all it’s properties with photon A except space-time. Calcite crystals are famously known for this, are they not? Both of you have grammatical mistakes btw.

          • TotallyRandomName

            Oh no! Just what horrible grammatical error did I make? I suppose that invalidates what I said. And sorry, calcite is common and plentiful. It doesn’t have any mystical properties. It does not “duplicate” photons, I have no idea where you read that. Whoever told you that has a gross misunderstanding of polarization. This crystal does nothing more than most sunglasses do.

          • Dennis Hastings

            Well, you’re kind of a jerk… You don’t start sentences with ‘and’, either. Just say what you have to say and leave out the YouTube vitriol. Rest easy with your superiority.

          • Alison Cowan

            And what is wrong with starting sentences with an indication that they are addendum to a previous sentence, instead of repeating the information in the previous sentence? Particularly in what is, in fact, conversation and not formal writing?

          • KevinShinn

            This rule of never ending a sentence with a preposition is nonsense up with which I will not put.~Winston Churchill

          • Randy patterson

            He’s implying quantum entanglement, I suppose. But one need look no further than Einstein’s paper on the photoelectric effect to get a fundamental idea of how an atom can “absorb” a photon, and emit one or more photons as a result.

  • Dana

    So they find one stone and they think that’s the stone all Vikings used? That’s a really weird, non-scientific way to “discover” something. I had heard the stone they used might have been iolite. I just double-checked and what do you know, iolite (cordierite) has pleochroism.

    A just-as-strong possibility is that both stones were used depending on which was available. It wasn’t as easy for them to find stones back then as it is for us now, so they likely used what they could find.

    • Randy patterson

      Some good points there, but they had indeed already mastered stonecutting at the time, and there was no shortage of stone, or effective methods of mining it

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