Citizen scientists discover a new auroral form: Dunes provide insight into the upper atmosphere

<p>Auroral forms are like fingerprints linking optical features to physical phenomena in the near-Earth space. While discovering new forms is rare, recently scientists reported of citizens' observations of STEVE, a pinkish optical manifestation of subauroral ionospheric drifts that were not thought to be visible to the naked eye. Here, we present a new auroral form named "the dunes". On Oct 7, 2018, citizen observers took multiple digital photographs of the same dunes simultaneously from different locations in Finland and Sweden. We develop a triangulation method to analyse the photographs, and conclude that the dunes are a monochromatic wave field with a wavelength of about 45 km within a thin layer at 100 km altitude. Supporting data suggest that the dunes manifest atmospheric waves, possibly mesospheric bores, which are rarely detected, and have not previously been observed via diffuse aurora, nor at auroral latitudes and altitudes. The dunes present a new opportunity to investigate the coupling of the lower/middle atmosphere to the thermosphere and ionosphere. We conclude that the the dunes may provide new insights into the structure of the mesopause as a response to driving by ionospheric energy deposition via Joule heating and electron precipitation. Further, our paper adds to the growing body of work that illustrates the value of citizen scientist images in carrying out quantitative analysis of optical phenomena, especially at small scales at subauroral latitudes. The dune project presents means to create general interest towards physics, emphasising that citizens can take part in scientific work by helping to uncover new phenomena.</p>

Phenomenology of Light

Focusing on the glitter of gold in a fourteenth-century Byzantine cross—today inserted in the famous reliquary of Cardinal Bessarion, Venice, Gallerie dell’Accademia—this chapter uncovers the important role phenomenology plays in the study of the spiritual operations of medieval art. The analysis draws on the inscriptions written on the cross in order to explore how gold’s sparkle functions as a vision of Paradise nourished by the Byzantine liturgy. This renewed engagement with the ephemerality of coruscation challenges the current neo-materialist turn in the humanities invested in semiotics, and argues by contrast that medieval matter is a medium of the spirit, whose descent and in-dwelling unfolds as a sensually saturated event and experience. Glitter, this chapter contends, enacts an optical manifestation—temporal and kinaesthetic—of divine ‘nearness’.