How could the Viking Sun compass be used with sunstones before and after sunset? Twilight board as a new interpretation of the Uunartoq artefact fragment
Vikings routinely crossed the North Atlantic without a magnetic compass and left their mark on lands as far away as Greenland, Newfoundland and Baffin Island. Based on an eleventh-century dial fragment artefact, found at Uunartoq in Greenland, it is widely accepted that they sailed along chosen lati...
Published in: | Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences |
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Online Access: | http://dx.doi.org/10.1098/rspa.2013.0787 https://royalsocietypublishing.org/doi/pdf/10.1098/rspa.2013.0787 https://royalsocietypublishing.org/doi/full-xml/10.1098/rspa.2013.0787 |
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crroyalsociety:10.1098/rspa.2013.0787 2024-06-02T08:03:50+00:00 How could the Viking Sun compass be used with sunstones before and after sunset? Twilight board as a new interpretation of the Uunartoq artefact fragment Bernáth, Balázs Farkas, Alexandra Száz, Dénes Blahó, Miklós Egri, Ádám Barta, András Åkesson, Susanne Horváth, Gábor 2014 http://dx.doi.org/10.1098/rspa.2013.0787 https://royalsocietypublishing.org/doi/pdf/10.1098/rspa.2013.0787 https://royalsocietypublishing.org/doi/full-xml/10.1098/rspa.2013.0787 en eng The Royal Society https://royalsociety.org/journals/ethics-policies/data-sharing-mining/ Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences volume 470, issue 2166, page 20130787 ISSN 1364-5021 1471-2946 journal-article 2014 crroyalsociety https://doi.org/10.1098/rspa.2013.0787 2024-05-07T14:16:44Z Vikings routinely crossed the North Atlantic without a magnetic compass and left their mark on lands as far away as Greenland, Newfoundland and Baffin Island. Based on an eleventh-century dial fragment artefact, found at Uunartoq in Greenland, it is widely accepted that they sailed along chosen latitudes using primitive Sun compasses. Such instruments were tested on sea and proved to be efficient hand-held navigation tools, but the dimensions and incisions of the Uunartoq find are far from optimal in this role. On the basis of the sagas mentioning sunstones, incompatible hypotheses were formed for Viking solar navigation procedures and primitive skylight polarimetry with dichroic or birefringent crystals. We describe here a previously unconceived method of navigation based on the Uunartoq artefact functioning as a ‘twilight board’, which is a combination of a horizon board and a Sun compass optimized for use when the Sun is close to the horizon. We deduced an appropriate solar navigation procedure using a twilight board, a shadow-stick and birefringent crystals, which bring together earlier suggested methods in harmony and provide a true skylight compass function. This could have allowed Vikings to navigate around the clock, to use the artefact dial as a Sun compass during long parts of the day and to use skylight polarization patterns in the twilight period. In field tests, we found that true north could be appointed with such a medieval skylight compass with an error of about ±4° when the artificially occluded Sun had elevation angles between +10° and −8° relative to the horizon. Our interpretation allows us to assign exact dates to the gnomonic lines on the artefact and outlines the schedule of the merchant ships that sustained the Viking colony in Greenland a millennium ago. Article in Journal/Newspaper Baffin Island Baffin Greenland Newfoundland North Atlantic The Royal Society Baffin Island Greenland Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470 2166 20130787 |
institution |
Open Polar |
collection |
The Royal Society |
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crroyalsociety |
language |
English |
description |
Vikings routinely crossed the North Atlantic without a magnetic compass and left their mark on lands as far away as Greenland, Newfoundland and Baffin Island. Based on an eleventh-century dial fragment artefact, found at Uunartoq in Greenland, it is widely accepted that they sailed along chosen latitudes using primitive Sun compasses. Such instruments were tested on sea and proved to be efficient hand-held navigation tools, but the dimensions and incisions of the Uunartoq find are far from optimal in this role. On the basis of the sagas mentioning sunstones, incompatible hypotheses were formed for Viking solar navigation procedures and primitive skylight polarimetry with dichroic or birefringent crystals. We describe here a previously unconceived method of navigation based on the Uunartoq artefact functioning as a ‘twilight board’, which is a combination of a horizon board and a Sun compass optimized for use when the Sun is close to the horizon. We deduced an appropriate solar navigation procedure using a twilight board, a shadow-stick and birefringent crystals, which bring together earlier suggested methods in harmony and provide a true skylight compass function. This could have allowed Vikings to navigate around the clock, to use the artefact dial as a Sun compass during long parts of the day and to use skylight polarization patterns in the twilight period. In field tests, we found that true north could be appointed with such a medieval skylight compass with an error of about ±4° when the artificially occluded Sun had elevation angles between +10° and −8° relative to the horizon. Our interpretation allows us to assign exact dates to the gnomonic lines on the artefact and outlines the schedule of the merchant ships that sustained the Viking colony in Greenland a millennium ago. |
format |
Article in Journal/Newspaper |
author |
Bernáth, Balázs Farkas, Alexandra Száz, Dénes Blahó, Miklós Egri, Ádám Barta, András Åkesson, Susanne Horváth, Gábor |
spellingShingle |
Bernáth, Balázs Farkas, Alexandra Száz, Dénes Blahó, Miklós Egri, Ádám Barta, András Åkesson, Susanne Horváth, Gábor How could the Viking Sun compass be used with sunstones before and after sunset? Twilight board as a new interpretation of the Uunartoq artefact fragment |
author_facet |
Bernáth, Balázs Farkas, Alexandra Száz, Dénes Blahó, Miklós Egri, Ádám Barta, András Åkesson, Susanne Horváth, Gábor |
author_sort |
Bernáth, Balázs |
title |
How could the Viking Sun compass be used with sunstones before and after sunset? Twilight board as a new interpretation of the Uunartoq artefact fragment |
title_short |
How could the Viking Sun compass be used with sunstones before and after sunset? Twilight board as a new interpretation of the Uunartoq artefact fragment |
title_full |
How could the Viking Sun compass be used with sunstones before and after sunset? Twilight board as a new interpretation of the Uunartoq artefact fragment |
title_fullStr |
How could the Viking Sun compass be used with sunstones before and after sunset? Twilight board as a new interpretation of the Uunartoq artefact fragment |
title_full_unstemmed |
How could the Viking Sun compass be used with sunstones before and after sunset? Twilight board as a new interpretation of the Uunartoq artefact fragment |
title_sort |
how could the viking sun compass be used with sunstones before and after sunset? twilight board as a new interpretation of the uunartoq artefact fragment |
publisher |
The Royal Society |
publishDate |
2014 |
url |
http://dx.doi.org/10.1098/rspa.2013.0787 https://royalsocietypublishing.org/doi/pdf/10.1098/rspa.2013.0787 https://royalsocietypublishing.org/doi/full-xml/10.1098/rspa.2013.0787 |
geographic |
Baffin Island Greenland |
geographic_facet |
Baffin Island Greenland |
genre |
Baffin Island Baffin Greenland Newfoundland North Atlantic |
genre_facet |
Baffin Island Baffin Greenland Newfoundland North Atlantic |
op_source |
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences volume 470, issue 2166, page 20130787 ISSN 1364-5021 1471-2946 |
op_rights |
https://royalsociety.org/journals/ethics-policies/data-sharing-mining/ |
op_doi |
https://doi.org/10.1098/rspa.2013.0787 |
container_title |
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences |
container_volume |
470 |
container_issue |
2166 |
container_start_page |
20130787 |
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1800748448401588224 |