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Extended magnetic reconnection at the Earth's magnetopause from detection of bi-directional jets


Magnetic reconnection is a process that converts magnetic energy into bi-directional plasma jets; it is believed to be the dominant process by which solar-wind energy enters the Earth's magnetosphere1,2. This energy is subsequently dissipated by magnetic storms and aurorae3,4. Previous single-spacecraft observations5,6,7 revealed only single jets at the magnetopause—while the existence of a counter-streaming jet was implicitly assumed, no experimental confirmation was available. Here we report in situ two-spacecraft observations of bi-directional jets at the magnetopause, finding evidence for a stable and extended reconnection line; the latter implies substantial entry of the solar wind into the magnetosphere. We conclude that reconnection is determined by large-scale interactions between the solar wind and the magnetosphere, rather than by local conditions at the magnetopause.

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Figure 1: Three-dimensional cutaway view of the magnetosphere showing the spacecraft positions and the presence of an extended reconnection line.
Figure 2: Overview of Equator-S and Geotail encounters of bi-directional jets.
Figure 3: Quantitative comparison with reconnection prediction.


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We thank R. Lepping and R. Lin for making the Wind spacecraft data available, and A. Raj, H. Kucharek, D. Patel and P. Schroeder for their help in the processing of Equator-S plasma data. We also thank S. Krucker for comments on the manuscript.

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Correspondence to T. D. Phan.

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Phan, T., Kistler, L., Klecker, B. et al. Extended magnetic reconnection at the Earth's magnetopause from detection of bi-directional jets. Nature 404, 848–850 (2000).

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