Mockup of the Swarm constellation. Image: ESA
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magnetic field for several decades now (the first ones had been detected
in the late 1960s),” study lead author Nicolas Gillet, from the Université Grenoble Alpes, said in an email. “We knew these were coming from changes in fluid motions of the core. The past two decades covered with satellite have shown that some kind of oscillatory behavior was occurring in the core.”“We were missing a dynamical explanation,” he continued. “The improved observational sampling has somewhat resonated with advances in both the numerical and theoretical sides; this lead to the discovery.”Earth's magnetic field sustains life on our planet by protecting us from cosmic radiation and other threats. It emanates from liquid iron in the core, and it's still rather mysterious, with constant fluctuations and a current phase of weakening that scientists are seeking to explain. Because of the important role that Earth's magnetic field plays in the survival of all planetside life, understanding it is of chief importance. The only practical way to globally analyze activity in the core is with readings from space, which is where the ESA's Swarm mission comes in. “What has allowed the unambiguous detection of these waves is the fact we now have continuous global coverage from space for two decades,” Gillet said. “However, we could see some signatures of these waves when only ground-based series were available. These were so far not understood.”
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core could be imaged in more details, helping us to better understand
its mechanism,” Gillet said to Motherboard. “But also the waves could help to constrain the electrical conductivity of the lower mantle (that they probe). This quantity is crucial to understand deep structures imaged by seismologists.”
”These waves also bring a possible explanation for magnetic changes
recorded on decadal and longer periods,” he continued. “As they offer a deterministic description of the signal, they may allow to partly predict magnetic changes.”Update: This article was updated with comment from study lead author Nicolas Gillet.