Uranus is known to be one of the “strangest” planets in the Solar System, but, as it turns out, its peculiarity may just be the result of an unfortunate coincidence. A recent study, published in Nature Astronomy and led by Jamie Jasinski of the California Institute of Technology (Caltech), suggests that the anomalies in Uranus' magnetic field, observed in 1986 by the Voyager 2 spacecraft, were caused by exceptionally intense solar activity, and not by some strange feature of the planet itself.
Distance and mystery
The outermost objects of the Solar System, such as Uranus, are difficult to study: they are located at enormous distances and probes take years to reach them, also facing enormous technological challenges and high costs. Uranus, for example, has only been visited up close once, in 1986, when Voyager 2 passed by it at a distance of 81,000 kilometres, collecting fundamental data on its atmosphere, internal structure and magnetic field.
The “solar wind” and the effect on Uranus data
During this historic passage, Voyager 2 recorded strong irregularities in Uranus' magnetic field, detecting asymmetries and the presence of highly energetic electrons. Until recently, these data were considered evidence of a unique and complex magnetic field, different from that of other gas giants such as Jupiter and Saturn.
But now, almost 40 years later, researchers have made a surprising discovery: in the days when the probe was flying over Uranus, the planet was hit by an intense wave of particles from the Sun. This solar wind would have altered the planet's magnetic field, deforming it to the point where it appeared to have special characteristics.
If Voyager 2 had passed just a week earlier...
If Voyager 2 had flown over Uranus even a week earlier, it would most likely have recorded a magnetic field similar to that of the other giant planets, with no obvious anomalies. This study changes the perspective on Uranus, suggesting that its “quirks” may depend more on external conditions than on real peculiarities of the planet.
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