Viking Sunstone

 

Modern replica of a Viking ship. Source

The Viking sunstone has been mentioned in various Icelandic texts throughout the 13th-15th centuries. It is said to have assisted Vikings in navigation when the sun was below the horizon or covered during an overcast day. One of the texts is the “Rauðúlfs þáttr“, it specifically mentions an account where the sunstone was used to locate the sun in overcast skies. Here is a translation of part of the text (Source):

“The weather was thick and snowy as Sigurður had predicted. Then the king summoned Sigurður and Dagur (Rauðúlfur’s sons) to him. The king made people look out and they could nowhere see a clear sky. Then he asked Sigurður to tell where the sun was at that time. He gave a clear assertion. Then the king made them fetch the solar stone and held it up and saw where light radiated from the stone and thus directly verified Sigurður’ s prediction”

Recently, a crystal was discovered in an Elizabethan ship wreck, and is believed to be an original sunstone artifact. Chemical analysis has shown that the artifact is made from calcite; in the past, it has been suggested that this could possibly have been the mineral that the Viking sunstones were made from. The reason for this is that calcite has an optical property called ‘birefringence’. This means that the speed at which light travels through the mineral varies depending on the polarization and propagation direction of the incident light rays.

A calcite crystal showing the effect caused due to birefringence.

To explain this in more detail I will use an analogy. Imagine you are pushing a pram along a footpath (light travelling through air), to the right of the footpath there is a lot of sand (a material other than air, in this case calcite). If the right hand wheels of the pram were to go in to the sand, the pram would be pulled in the direction of the sand because the pram travels slower in sand. When this happens with light going from air to another material such as water or glass, it is called diffraction. The difference with calcite is that that change in speed depends on the angle that the light enters the crystal and also the polarization of the light waves.

This image shows how light rays polarized in different orientations diffract by different amounts. This is what causes the doubling effect seen in the picture above.

So what does this have to do with calcite being the sunstone? If you were to hold a calcite crystal up to the horizon and rotate around, you would see the doubling effect occur at different angles from the sun due to the change in polarization of light entering the atmosphere. If you were facing the direction of the sun, the double image would begin to line up as the light would be all polarized in the same direction. This would allow you to know which direction you are travelling and therefore whether you were on the right path or not.

The sunstone had been thought of as just a legend for quite some time, but the recent discovery mentioned above adds much credibility to the mentions of this fascinating object in historical texts.

Bugs Are Eating the Titanic

Everybody knows the story of the ill-fated Titanic; sinking into the Atlantic Ocean on April 15^th, 1912, after striking an iceberg. Famed maritime archaeologist Robert Ballard located the wreck on the ocean floor in 1985, and since then, several dives have provided photographic evidence of the Titanic’s condition. Certain expeditions have salvaged artifacts from the wreck, now on display in museums, and others have made attempts to raise the wreck. Unfortunately, it cannot be raised, as it has become too delicate from the deterioration that has occurred in the hundred years since its sinking.

The bow of the Titanic wreck – 2004

However, icebergs, cold waters and great depths will no longer be the only problem facing prospective researchers. A newly-identified bacterial species has colonized the wreck, and there is something quite special about these bugs. Halomonas titanicae, as it is known in the scientific community, likes to eat iron. These bugs are consuming the iron in the Titanic’s hull and main structure at a rapid pace, leaving behind rust as a waste product, and forming things that are known as ‘rusticles’, which disintegrate upon being touched. Rusticles already cover a large proportion of the wreck, and at some stage in the future, most of the Titanic’s main structure and hull will have disappeared, consumed by these hungry bacteria.

Rusticles hanging from the hull of the Titanic wreck – 2003

While it is sad that the famous wreck will one day be gone for good, H. titanicae may actually prove to be useful in some aspects. One day, they could be used to aid in the disposal of old ships and oil-rigs. Furthermore, now that we are aware of their existence, scientists can begin research into the creation of a protective coating that can be applied to ships and underwater pipelines to prevent H. titanicae from doing any damage. Overall, they are a very interesting species, and it makes you wonder what other amazing creatures are lurking in the great ocean depths.

For more information, see “Titanic is being devoured by steel-munching bacteria, say scientists.” Europe Intelligence Wire 6 Dec. 2010. General OneFile. Web. 21 Mar. 2013.

The Mystery of Bouvet Island

Picture showing the west coast of Bouvet Island.
Credit to François Guerraz

The freezing subantarctic Bouvet Island is literally in the middle of nowhere; located in the South Atlantic Ocean, it is known for being the most remote island in the entire world. A Norwegian dependency, it is a very small, uninhabited island, and is now classified as a nature reserve after a weather station operated on it for a few months during 1978 and 1979. Aside from its unfathomable isolation, there doesn’t seem to be anything all that special about this island at first glance.

In 1964, British Lieutenant Commander Allan Crawford and a team were sent to Bouvet Island by helicopter, to research a new piece of land that had popped up on the island due to volcanic activity. Here’s where it gets a bit weird. When they arrived, they found something very unusual. On this new patch of land, which had only been there for around ten years, the team came across an abandoned lifeboat, floating in a lagoon. The oars were on the shore, along with a copper tank.  There were no signs of any people or bodies, and the boat was unmarked and thus unidentifiable as belonging to anyone in particular. Unfortunately, the team did not have much time to look around, but before they left they snapped this photo:

So, where did the boat come from? It’s possible that it came from a ship in distress, but that theory has been seen as doubtful because of the sheer remoteness, minuscule size and lack of visibility of the island due to the harsh weather. Even if it was a shipwreck victim, where did they go? As mentioned previously, there were no signs that anyone had tried to camp near the lifeboat, or attempted to use it as a shelter. It’s also possible that it just happened to wash up near the island, coming to rest in the lagoon after floating in from a shipwreck hundreds of miles away, but this doesn’t explain the oars and other equipment on the shore.

From here, the mystery deepens. Another expedition to the island a couple of years later found no traces of the boat, the oars or the copper tank. Did the owner of the boat come back to fetch it? This seems unlikely, again due to the general remoteness of the island, coupled with the fact that retrieving a lifeboat would mean lifting it out with a helicopter or dragging it back out to sea and placing it on a ship; both just seem like way too much effort to go to for something as insignificant as a lifeboat.The whole thing is very mysterious, and quite creepy to think about. I have two theories:

1. The lifeboat did belong to a shipwreck victim who had simply happened to come across the island by pure chance. Landing on the shore, he left the boat (which was obviously too heavy to carry around) and went to look for some kind of food and water sources. The severe climate may have been too much for him to handle, and he could have collapsed and died elsewhere on the island whilst doing this. As stated above, the team that found the boat didn’t have time to search much further than the shore where the boat was, so this seems like a logical explanation. There are still several questions remaining, though. Were there any shipwrecks in the general vicinity of the island at the time? If so, why didn’t anyone come forward to claim the boat and say it was from their ship? Where did the boat disappear to? Maybe the boat somehow floated back out to sea, or simply sank into the lagoon. Unfortunately, there is no real way of knowing.
2. A larger ship was in the area on an expedition, and sent a team with a couple of smaller boats to land on the shore. When they landed, they noticed that one of the boats was slightly damaged, and the team all headed back on the good boat, got back on the ship and left, after exploring the island. This would explain why there were no signs of any camping activity or human remains. As the team who found the boat in 1964 spent very little time on the island, perhaps they didn’t notice the boat was slightly damaged. This still doesn’t explain where the boat disappeared to, though, and again, if this theory is correct, why didn’t anyone come forward to say that it was their boat?

Either way, the mystery of the boat on Bouvet Island remains unsolved. I doubt anyone will ever know the exact reason behind it, but anyone with other theories is welcome to list them in the comments below.

For more in-depth information on this topic, please see http://allkindsofhistory.wordpress.com/2011/02/13/an-abandoned-lifeboat-at-worlds-end/.