Secrets of the Viking Sun-Compass -- After Dark
This wooden fragment discovered in Uunartoq, Greenland, in 1948 has long been thought to be a sun-compass used to determine direction. Could crystals have been applied to make it work after dark?
We all enjoy a tall tale. Cultures with seafaring traditions are especially ripe in what seem like the tallest sea monster tales of all: hydra, kraken, sirens, scylla, leviathans, assorted serpents and mermaids. Usually the stories are never confirmed and usually baseless.
Then again, some of the tales are based on something, or so we are learning as marine scientists plumb the depths and discover some pretty weird creatures. The bottom line: There really are bizarre, unexpected, totally startling monsters found in the seas. And the very worst of these is the most unexpected.
Sea monsters are truly global. This one from Japan serves as the villain for the classic maiden in distress, who awaits rescue by her hero. The poor monsters are almost always cast as the bad guys. And so they usually end hacked to pieces; fish food.
But is there any truth behind these sea serpent tales?
Credit: NOAA/ Bloodydecks.com
Improbable, But True
Maybe it's the oarfish. It looks too monstrous to be true. It can grow many meters long, has strikingly bright silver scales, scarlet fins and some ornate headgear that more than explains why some call it a roosterfish. If only it were a reptile, it'd be a true sea serpent.
Alas. It is a fish. A very weird and beautiful fish, but still a fish.
Largest Serpent of All
There are also other, newfound "sea serpents" our sea-going ancestors never imagined. This one was spotted by a satellite coiling off the south coast of Japan's Hokkaido island.
What do we know about it? 1) It's arguably one of the largest organisms on Earth, 2) It swallows ships, engulfs islands and generally does what it wants, and 3) We're darned lucky it's made of plankton.
Research into such massive blooms and the individual plankton cells that comprise them has revealed surprising cooperation among the microorganisms. They appear to operate like more than just floating individual cells. They live and die for the greater good, it seems. So they may be, in fact, a gigantic watery superorganism.
Now that's a cool monster for you: You can swim in it and never know you've been in the belly of a beast.
The Hokey Hybrids
Mermaids and mermen have always been the stuff of fantasy. Where did the fantasies come from? There are some standard answers to this question, which have always seemed rather inadequate. For instance ... (next slide, if you please) ...
Credit: Getty Images
The manatee has often been called the source of mermaid myths. It's a mammal, so it breathes air. But who would ever mistake a manatee for a sleek and beautiful mermaid?
Could it be love-starved sailors with poor eyesight? There was no shortage of these fellows in the days before optometrists.
Credit: beats me
Another possibility is that merfolk were inspired by fish with roughly human-looking faces, like this fellow. Some fish can look humanoid. That would be enough to get superstitious sailors started.
The Kraken Strikes
How about giant, ship-destroying squid and octopi? These monsters were old hat even to the easily freaked-out. Most folks figured they were historical exaggerations.
That's until some very large and unusual squids started washing up or being hauled in by marine biologists in recent years. Colossal squid are meters long, pretty amazing beasts. Still, they have never been known to lift ships out of the water.
And since were on the topic of squids ...
Spider + Bat + Squid = Sea Monster
Do you remember when this one hit the headlines? It's not so gigantic, at four meters long, but it was observed 3,380 meters down in the Pacific Ocean near Oahu. It's pretty big to have gone unseen before its May 2001 discovery.
So what else is out there? It's pretty clear marine biologists have only just begun discovering what lives in the deep sea. The more time they spend searching, the more they will find. But none would dispute that the nastiest sea monster to ever rise out of the sea is ... (drum roll please) ...
Deadliest Sea Monster Ever
You might have guessed it: Human garbage. Yep. It's the ugliest, most alien-looking, fatal and pervasive monster in the seas. Garbage patches have been getting a lot of attention lately. These are areas on the seas where currents and winds tend to concentrate floating garbage.
Viking sailors may have been able to navigate after sunset, despite having no magnetic compasses and relying on sun compasses, says a team of researchers from Hungary and Sweden.
The trick may have been to combine the power of a sun-compass, which is a sort of modified sundial, with that of sunstones to create what they are calling a "twilight board."
"The recently identified calcite crystal found between the navigational tools of 16th-century European ship wreck hints that they could play some role in marine navigation" reports Balázs Bernáth and his colleagues in the Proceedings of the Royal Society A.
To test out if such twilight boards might have existed, the team examined a fragment of an 11th-century dial found in Uunartoq, Greenland, and attempted to extrapolate its features into something that would allow Viking navigators to detect the position of the sun from the twilight glow on the horizon passing through two sunstones.
If the Uunartoq dial is a fragment of a twilight board, the notches in the upper part would indicate true north, instead of a few degrees off, as has been interpreted by others. Lines scratched into the dial fit the path of a low shadow on March 10 and 31, which straddle the equinox. The dial would be used along with two calcite "sunstones" that would find the position of the sun below the twilight horizon. Image adapted from Bernáth, et al., PRSA
If the difficult technique was employed, it could have allowed navigation well after sunset, since the twilight glow can last all night long at high latitudes in summer. Sunstones are recorded in Viking sagas as being employed to navigate on cloudy days, although what the stones were and how they worked remains lost knowledge.
The first step in regaining that knowledge was taken a few years ago by physicist Guy Ropars of the University of Rennes in France. Ropars and his team experimented with a potential sunstone that was recovered from a British ship which sunk in 1592. They applied partially polarized laser light on the calcite crystal -- similar to the kind of light that would make it through clouds (direct, unfiltered sunlight is not polarized).
By turning the crystal they found that a single angle where the crystal splits the light and transmits both unpolarized and polarized light beams at equal strength. This angle of equal brightness of the two beams of light in the crystal could be used by navigators to then determine the angle of the sun in the sky -- without actually being able to see the sun.
The twilight board would have used the same approach, argues Bernáth, but instead of being used during the day to navigate under clouds, it would use the light in the sky after sunset, along with a specially marked dial, perhaps one like that found in Uunartoq.
"Developing a twilight board is surely not beyond the capabilities of sea-faring people," Bernáth opined. "Sunstones are mentioned in written sources and they could be used during civil twilight, although it is not trivial how one can accurately estimate the position of the sun with them."
Ropars, for his part, is somewhat doubtful that the twilight boards existed.
"(Bernáth and his team) propose to use simultaneously two calcite sunstones in two different directions for determining the Sun position, inducing inevitably a loss of accuracy," Ropars told Discovery News. "Moreover this method seems to be difficult to be applied by Vikings."
The bottom line, according to Bernáth, is that there are just not enough Viking navigational artifacts to prove the case. Small navigational tools would likely not preserve well, but he holds out hope that something important might exist, unrecognized, in some modern museum collections.