At the beginning of the twentieth century, the well-known Norwegian polar explorer Fridtjof Nansen described his encounter with the Northern Lights:

One of the most captivating and suggestive celestial spectacles, the Northern Lights or aurora borealis are a display of light in the northern hemisphere caused by the interaction between the solar wind and the upper atmosphere. This ephemeral and shape-shifting astronomical occurrence remained mysterious until the nineteenth and twentieth centuries, when explorers like Nansen began to give more accurate descriptions of the phenomenon, comparing the Northern Lights to the manifold colours of the rainbow. The aurora's explosion of energy and colours and its rapid movements often cause flickering shapes in the sky, the most common described as armies in the sky, spears, torches, and fiery dragons. It is not surprising, then, that such a phenomenon would appeal to the imagination of observers, and naturally acquire a mystical dimension. Notwithstanding the nearly 1,200 years which separate the two accounts, a similar, albeit shorter and less detailed, depiction of the natural phenomenon seems to appear in what is perhaps one of the most celebrated and evocative accounts in Old English literature, the entry in the Anglo-Saxon Chronicle (henceforth ASC) for the year 793, which details the sack of Lindisfarne by the Vikings and which the chronicler deliberately associates with fyrenne dracan in the sky, and ormete þodenas 7 ligrescas: