11 April 2002

Geophysics: Twenty years in the life of Earth's magnetic field

The Oersted satellite (the pencil-shaped one on the cover) is now in orbit collecting data on Earth's magnetic field. Comparison of its results with those from Magsat, operational in 1980, makes it possible to plot small-scale variations in the magnetic field over the past 20 years. Strong changes in the field are seen in two regions. The present state of the geodynamo resembles those seen in numerical simulations, and its asymmetric nature is suggestive of conditions that might be reached before a reversal of the Earth's magnetic field.

Small-scale structure of the geodynamo inferred from Oersted and Magsat satellite data
GAUTHIER HULOT, CÉLINE EYMIN, BENOÎT LANGLAIS, MIOARA MANDEA & NILS OLSEN
Nature 416, 620–623 (11 April 2002)
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Geophysics: The disappearing dipole
PETER OLSON
Satellite measurements of the Earth's magnetic field reveal a detailed picture of the circulation in the liquid iron core. The data suggest that the planet could be in the early stages of reversing its magnetic polarity.
Nature 416, 591–594 (11 April 2002)
| Full Text | PDF (162 K) |

11 April 2002 table of contents