"Think of it as a fuzzy boundary between the mantle and the core, with patches perhaps 10 to 20 km (6 - 12 miles) across and up to a 1, 000 metres (3, 280 ft) thick, " Jeanloz said.

BBC: Earth's wobbles reveal deep secrets

Under the Hood: 3.7 liter DOHC 24-valve VVEL V6 Engine, 330 hp and 27 lb-ft torque.

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