David Whitehouse at the BBC News:
The Vikings could have been using a telescope hundreds of years before Dutch spectacle makers supposedly invented the device in the late 16th century.
This remarkable possibility has emerged from a study of sophisticated lenses just recognised from a Viking site on the island of Gotland in the Baltic Sea. They were initially thought to be merely ornaments.
“It seems that the elliptical lens design was invented much earlier that we thought and then the knowledge was lost,” says Dr Olaf Schmidt, of Aalen University in Germany.