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Saturn's elusive nightside polar arc
Author(s) -
Radioti A.,
Grodent D.,
Gérard J.C.,
Milan S. E.,
Fear R. C.,
Jackman C. M.,
Bonfond B.,
Pryor W.
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl061081
Subject(s) - saturn , astrobiology , polar , arc (geometry) , geology , geophysics , astronomy , physics , planet , geometry , mathematics
Nightside polar arcs are some of the most puzzling auroral emissions at Earth. They are features which extend from the nightside auroral oval into the open magnetic field line region (polar cap), and they represent optical signatures of magnetotail dynamics. Here we report the first observation of an arc at Saturn, which is attached at the nightside main oval and extends into the polar cap region, resembling a terrestrial transpolar arc. We show that Earth‐like polar arcs can exceptionally occur in a fast rotational and internally influenced magnetosphere such as Saturn's. Finally, we discuss the possibility that the polar arc at Saturn is related to tail reconnection and we address the role of solar wind in the magnetotail dynamics at Saturn.