Just published – an astronomical interpretation of the prehistoric cup and ring carvings discovered in Ashover and at certain sites further north, linking them to the dawn rising of specific constellations at key dates in the agricultural year. It is suggested that these petroglyphs may have featured in communal celebrations thanks to simulating key constellations by reflections in moonlight or torchlight. A quantitative method of assessing similarities between constellations and petroglyphs is proposed which appears to corroborate the suggested method of mapping the sky, by explaining systematic distortion. It is hoped that this publication might stimulate further enquiries into the meaning of a ubiquitous feature of our northern landscapes.