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On the trail of Vikings with polarized skylight: experimental study of the atmospheric optical prerequisites allowing polarimetric navigation by Viking seafarers

Horvath, Gabor; Barta, Andras; Pomozi, Istvan; Suhai, Bence; Hegedues, Ramon; Åkesson, Susanne LU ; Meyer-Rochow, Benno and Wehner, Ruediger (2011) In Royal Society of London. Philosophical Transactions B. Biological Sciences 366(1565). p.772-782
Abstract
Between AD 900 and AD 1200 Vikings, being able to navigate skillfully across the open sea, were the dominant seafarers of the North Atlantic. When the Sun was shining, geographical north could be determined with a special sundial. However, how the Vikings could have navigated in cloudy or foggy situations, when the Sun's disc was unusable, is still not fully known. A hypothesis was formulated in 1967, which suggested that under foggy or cloudy conditions, Vikings might have been able to determine the azimuth direction of the Sun with the help of skylight polarization, just like some insects. This hypothesis has been widely accepted and is regularly cited by researchers, even though an experimental basis, so far, has not been forthcoming.... (More)
Between AD 900 and AD 1200 Vikings, being able to navigate skillfully across the open sea, were the dominant seafarers of the North Atlantic. When the Sun was shining, geographical north could be determined with a special sundial. However, how the Vikings could have navigated in cloudy or foggy situations, when the Sun's disc was unusable, is still not fully known. A hypothesis was formulated in 1967, which suggested that under foggy or cloudy conditions, Vikings might have been able to determine the azimuth direction of the Sun with the help of skylight polarization, just like some insects. This hypothesis has been widely accepted and is regularly cited by researchers, even though an experimental basis, so far, has not been forthcoming. According to this theory, the Vikings could have determined the direction of the skylight polarization with the help of an enigmatic birefringent crystal, functioning as a linearly polarizing filter. Such a crystal is referred to as 'sunstone' in one of the Viking's sagas, but its exact nature is unknown. Although accepted by many, the hypothesis of polarimetric navigation by Vikings also has numerous sceptics. In this paper, we summarize the results of our own celestial polarization measurements and psychophysical laboratory experiments, in which we studied the atmospheric optical prerequisites of possible sky-polarimetric navigation in Tunisia, Finland, Hungary and the high Arctic. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Viking navigation, sky polarization, imaging polarimetry, atmospheric, optics
in
Royal Society of London. Philosophical Transactions B. Biological Sciences
volume
366
issue
1565
pages
772 - 782
publisher
Royal Society
external identifiers
  • wos:000286721400020
  • scopus:79952347219
ISSN
1471-2970
DOI
10.1098/rstb.2010.0194
project
CAnMove
language
English
LU publication?
yes
id
7cd3de4b-7b6c-4c61-999d-f38e1d902c7c (old id 1925736)
date added to LUP
2011-05-11 08:43:59
date last changed
2017-10-22 04:20:56
@article{7cd3de4b-7b6c-4c61-999d-f38e1d902c7c,
  abstract     = {Between AD 900 and AD 1200 Vikings, being able to navigate skillfully across the open sea, were the dominant seafarers of the North Atlantic. When the Sun was shining, geographical north could be determined with a special sundial. However, how the Vikings could have navigated in cloudy or foggy situations, when the Sun's disc was unusable, is still not fully known. A hypothesis was formulated in 1967, which suggested that under foggy or cloudy conditions, Vikings might have been able to determine the azimuth direction of the Sun with the help of skylight polarization, just like some insects. This hypothesis has been widely accepted and is regularly cited by researchers, even though an experimental basis, so far, has not been forthcoming. According to this theory, the Vikings could have determined the direction of the skylight polarization with the help of an enigmatic birefringent crystal, functioning as a linearly polarizing filter. Such a crystal is referred to as 'sunstone' in one of the Viking's sagas, but its exact nature is unknown. Although accepted by many, the hypothesis of polarimetric navigation by Vikings also has numerous sceptics. In this paper, we summarize the results of our own celestial polarization measurements and psychophysical laboratory experiments, in which we studied the atmospheric optical prerequisites of possible sky-polarimetric navigation in Tunisia, Finland, Hungary and the high Arctic.},
  author       = {Horvath, Gabor and Barta, Andras and Pomozi, Istvan and Suhai, Bence and Hegedues, Ramon and Åkesson, Susanne and Meyer-Rochow, Benno and Wehner, Ruediger},
  issn         = {1471-2970},
  keyword      = {Viking navigation,sky polarization,imaging polarimetry,atmospheric,optics},
  language     = {eng},
  number       = {1565},
  pages        = {772--782},
  publisher    = {Royal Society},
  series       = {Royal Society of London. Philosophical Transactions B. Biological Sciences},
  title        = {On the trail of Vikings with polarized skylight: experimental study of the atmospheric optical prerequisites allowing polarimetric navigation by Viking seafarers},
  url          = {http://dx.doi.org/10.1098/rstb.2010.0194},
  volume       = {366},
  year         = {2011},
}