Northern Lights - 30 Years of Collaboration

by Valentina Giangreco M. Puletti 7 Nov 2013 International Cooperation
Published in the "Nordic News" section of Nordita News issue 3, 2013

On 4th September, Prof. Natsuo Sato of the Nationational Institute of Polar Research in Japan, gave a talk on research activities on conjugate aurora borealis done in cooperation between the Japanese National Institute of Polar Research and the Science Institute, University of Iceland for the past 30 years.

A conjugate point pair is defined as the intersection of a given magnetic field line with the Northern and Southern Hemispheres. Magnetic field lines, linking the Earth's polar regions, connect either to the opposite hemisphere (closed field lines) or to the interplanetary magnetic field (open field lines). Charged particles in the magnetosphere move along magnetic field lines and thus it is commonly assumed that the aurora borealis (Northern Hemisphere) and aurora australis (Southern Hemisphere) are mirror images of each other. However, 30-year conjugate observations show that occurrences of mirror image aurora are rare. In general, Optical observations of these events are difficult since the observations at two conjugate points must be done simultaneously, but for that to happen, both observatories must be in darkness and both should have fine weather. In spite of these limitations, Icelandic and Japanese scientists have obtained many interesting auroral events. Measurements of inter-hemispheric conjugate aurora provide a unique opportunity to investigate how and where the invisible geomagnetic field lines connect the two hemispheres, the influence of the solar wind on the Earth's magnetosphere and the nature of the auroral acceleration process. [Read more...]