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.
