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Uranus is more normal than we had thought<\/p>\n
NASA\/Space Telescope Science Institute<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
Uranus\u2019s strange magnetic field may be much less weird than astronomers first thought, which means its largest moons could be much more active, and even perhaps have global oceans.<\/p>\n
Our only direct measurements of Uranus\u2019s magnetic field come from NASA\u2019s Voyager 2 spacecraft, which flew by the planet in 1986. The spacecraft\u2019s readings suggested that the magnetic field was lopsided \u2013 meaning it wasn\u2019t aligned with the planet\u2019s rotation \u2013 as well as being unusually rich in extremely energetic electrons and devoid of the plasma that is common in the magnetic fields of other gas giants like Jupiter. Astronomers at the time thought the results so bizarre that they invoked complex physics to try to explain the readings \u2013 or simply dismissed them as evidence that Voyager 2\u2019s instruments had gone haywire.<\/p>\n
Now, Jamie Jasinski at NASA\u2019s Jet Propulsion Laboratory in California and his colleagues have reanalysed the Voyager 2 data and found that it was skewed by a rare burst of solar wind that squashed Uranus\u2019s magnetic field just before the spacecraft arrived, disturbing the readings. This means everything we thought we knew about Uranus\u2019s magnetic field might be wrong, says Jasinski. \u201cThis kind of almost resets everything,\u201d he says.<\/p>\n
<\/p>\n Jasinski and his team found that the solar wind compressed Uranus\u2019s magnetic field to a size that it would typically only adopt 4 per cent of the time \u2013 but that scientists have, for the past 40 years, assumed was its normal state. The squashed magnetic field explains the previous strange results, such as its lack of plasma and highly energetic electrons, says Jasinski.<\/p>\n If there is, in fact, plasma in Uranus\u2019s magnetic field \u2013 and Voyager 2 just happened to miss it \u2013 then it might not all come from the planet itself. Some might come from Uranus\u2019s moons, the largest of which are called Titania and Oberon. Until now, we have assumed these moons were inert, but the new study leaves open the possibility that they are geologically active after all. This would fit with recent calculations indicating the moons might have hidden oceans. \u201cThe solar wind could have essentially eradicated all the evidence of active moons just before the flyby happened,\u201d says Jasinski.<\/p>\n Topics:<\/p>\n<\/section><\/div>\n