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:

A Significant corpus of Anglo-Saxon prognostics survives in various eleventh- and twelfth-century manuscripts. Until recently these texts have been erroneously and superficially associated with magic and pagan worship, without regard to the cultural context of the manuscripts which contain them. Scholars have shown a deeper interest in more obviously mainstream monastic works such as homilies and saints' lives, on the assumption that prognostics were not part of that mainstream religious culture of the period.

Another feature which has deterred scholars from sustained engagement with this material is its diversity. It comprises a miscellaneous assortment of texts both in Latin and English, ranging from the occurrence of wind and sun during the twelve nights of Christmas, predictions based on the weather on Christmas Day and New Year's Day, known as the Revelatio Esdrae, to lists of lucky and unlucky days, the prediction of an individual's character and personality from the day of the week in which he was born, dream prophecies, thunder divination, and much besides. Prognostics are calendrical, rather than astrological, in the sense that they are generally placed within a specific time framework which could be the days of the week, months and years.

This remarkable corpus of Old English predictions has remained obscure to modern readers and students until recently. Building on Max Förster's haphazard but valuable series of articles dispersed between Englische Studien and Archiv für das Studium der neueren Sprachen und Literaturen (1903–25), L. S. Chardonnens published, in 2007, the first comprehensive edition of Anglo-Saxon prognostics in both Latin and English.