Based on their reputation and looks, the Vikings would not have had any trouble getting directions, maps or even just fingers pointed in the right direction from terrified people encountered on their trips. Now new evidence suggests they wouldn’t have needed to … even at night.

The journal Proceedings of the Royal Society A reports on a study by researchers at Eötvös Loránd University in Hungary which may prove that the Vikings found a way to use the Uunartoq disc sundial compass after sunset.

Uunartoq disc

After creating a model of a complete disc using the partial one found in Greenland in 1948, the researchers surmised that the Vikings placed a low domed object in the middle of the disc instead of a conventional sundial spike, creating a wider shadow.

To locate the sun after sunset, they speculated the Vikings used a pair of sunstones – calcite crystals that produce patterns when exposed to even low-level UV rays. The orientation of these patterns on the disc would help pinpoint the position of the sun below the horizon.

Sunstones

Tests of this twilight compass returned accurate results within 4 degrees of error.

Medieval records show the Vikings had access to the sunstones. Did they use them? It’s still speculation but who’s going argue with a Viking!