Astrophysicist uncovers secrets of red sprites

Brno, 14 March 2016

Graduated student in astrophysics at Masaryk University, Petr Horálek, captured unique images of red sprites, mysterious, atmospheric phenomena occurring during massive storms. His rare catch Petr acquired during his work as a photographer at ESO's La Silla and Paranal observatories in Chile. The management of the European Southern Observatory was so enthusiastic about those images that they invited this Czech photographer as director and script writer for making a popularizing video, which is dedicated to those still mysterious nadoblačným lightning.

Petr Horálek, which ranks among the best photographers of the night sky in the world, was invited by the European Southern Observatory (ESO) to photograph the beauty of the starry sky over La Silla and Paranal observatories, in the heart of the Atacama Desert. This arid region lying moreover far from the light pollution is a particularly appropriate place for astronomical observations. It is therefore not surprising that ones of the largest observatories in the world stand there. Petr spent at these observatories one week in January, and devoted himself to photographing uniquely dark night sky with the Milky Way and other jewels of the southern sky in the background of ESO telescopes. During the first night Peter was surprised by flashes of reddish-shaped tassels, flickering on the distant horizon. These atmospheric discharges was accompanied by a massive storm system over Argentina, raging at a distance of 550 km!

Red sprites, as they are called transient luminous events, are the most common type of so-called uper-cloud lightning. Although their incidence is statistically the most common they are for their elusiveness very elusive. They last for a mere fractions of seconds and only the most prominent of them manage to record. Their formation is associated with massive convective storms - at the time a powerful electric discharge between cloud and ground is formed, the red sprite in the stratosphere counterpart flashes. A characteristic red radiation from nitrogen gives them a typical reddish hue. Since the sprites appear in heights between 50 and 90 kilometers above the earth, they can be observed from enormous distances.

Peter's records of red sprites are so eye-catching and unique, that they earned well as a separate part in a series of instructional videos ESOcast produced directly by ESO. Peter's experience and knowledge moved him to the post of director and screenwriter, so he was able to point to other documented atmospheric phenomenon - density waves. These arise as a result of severe storms and appear as a significant discontinuity in air density. They can be observed by using greenish atmosphere radiation, called airglow, which is thicker at places with higher density. Everything is processed in an engaging video, whose author is, for the first time in the history of the European Southern Observatory, Czech.

Peter Horálek contact: horalek@astro.cz, web

Images of red sprites by Peter Horálek: zde

Mgr. Lenka Zychová, zychova@physics.muni.cz