A magnetic reconnection X-line extending more than 390 Earth radii in the solar wind

T. D. Phan, J. T. Gosling, M. S. Davis, R. M. Skoug, M. Øieroset, R. P. Lin, R. P. Lepping, D. J. McComas, C. W. Smith, H. Reme, A. Balogh

Research output: Contribution to journalArticlepeer-review

246 Scopus citations


Magnetic reconnection in a current sheet converts magnetic energy into particle energy, a process that is important in many laboratory1, space2,3 and astrophysical contexts4-6. It is not known at present whether reconnection is fundamentally a process that can occur over an extended region in space or whether it is patchy and unpredictable in nature7. Frequent reports of small-scale flux ropes and flow channels associated with reconnection8-13 in the Earth's magnetosphere raise the possibility that reconnection is intrinsically patchy, with each reconnection X-line (the line along which oppositely directed magnetic field lines reconnect) extending at most a few Earth radii (RE), even though the associated current sheets span many tens or hundreds of R E. Here we report three-spacecraft observations of accelerated flow associated with reconnection in a current sheet embedded in the solar wind flow, where the reconnection X-line extended at least 390RE (or 2.5 × 106 km). Observations of this and 27 similar events imply that reconnection is fundamentally a large-scale process. Patchy reconnection observed in the Earth's magnetosphere is therefore likely to be a geophysical effect associated with fluctuating boundary conditions, rather than a fundamental property of reconnection. Our observations also reveal, surprisingly, that reconnection can operate in a quasi-steady-state manner even when undriven by the external flow.

Original languageEnglish (US)
Pages (from-to)175-178
Number of pages4
Issue number7073
StatePublished - Jan 12 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General


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