Published: 21 June 2021
New Topical Collection in Space Science Reviews (partial Open Access)
The new article collection on “Auroral Physics” is designed to provide a comprehensive review of our current scientific understanding of the terrestrial aurora, both observational and theoretical, with an emphasis on developments since a previous collection devoted to the terrestrial aurora, “Auroral Plasma Physics” (Space Science Reviews volume 103, 2002, by G. Paschmann, S. Haaland, and R. Treumann). That collection emphasizes introductory and background material which is not repeated in the current set.
The term “aurora borealis”, or “northern dawn” dates back centuries and refers to emissions of light from the otherwise-dark nighttime atmosphere, usually occurring in the polar regions except during highly disturbed periods. Aurora is distinct from airglow, which is a weak and relatively unstructured emission in the thermosphere caused by chemical reactions and ionization driven primarily by solar UV illumination during the day. In contrast, auroral emissions are the result of excitation of neutral atoms and molecules in the upper atmosphere by collisions with charged particles, typically which originate in the magnetosphere and precipitate along geomagnetic field lines with energies of hundreds of eV to tens of keV.
Popular descriptions of the aurora including in the media, dictionaries, encyclopedias and even textbooks often claim that the aurora is caused by “particles from the sun striking the upper atmosphere”. It is well established in auroral science that such a description is not accurate except in very limited cases. While it is certainly true that particles from the sun – the solar wind – provide the energy that drives the aurora, the widely varying morphologies and behaviors of the aurora are the result of a complex chain of events that take place within Earth’s magnetosphere or at its boundary, the magnetopause. The end result of this chain – excitation of neutrals by charged particles – is also well-established fact, as are many other aspects described in this collection. However, due to the vast region of the magnetosphere that is magnetically conjugate to the auroral ionosphere, and the difficulty in sampling it with a single or even multiple spacecraft, the nature of the magnetospheric generator responsible for driving individual auroral forms still remains one of the most elusive aspects of the aurora.
Planning for this Topical Collection took place during a workshop hosted in August 2018 by the International Space Science Institute (ISSI), in Bern (Switzerland), and attended by more than 40 members of the international scientific community.
This Topical Collection will be reprinted as the Volume 78 in the Space Sciences Series of ISSI and is edited by David Knudsen, Joe Borovsky, Tomas Karlsson, Ryuho Kataoka and Noora Partmies.
Introductory article:
David Knudsen, Joe Borovsky, Tomas Karlsson, Ryuho Kataoka and Noora Partmies. Editorial: Topical Collection on Auroral Physics, Space Sci Rev 217, 19 (2021). https://doi.org/10.1007/s11214-021-00798-8
