關於金星磁場直接複製一段
A dynamo requires three things: A conducting liquid, rotation, and convection. The core is thought to be electrically conductive and, while its rotation is often thought to be too slow, simulations show it is adequate to produce a dynamo. This implies the dynamo is missing because of a lack of convection in the Venusian core. On Earth, convection occurs in the liquid outer layer of the core because the bottom of the liquid layer is much hotter than the top. On Venus, a global resurfacing event may have shut down plate tectonics and led to a reduced heat flux through the crust. This caused the mantle temperature to increase, thereby reducing the heat flux out of the core. As a result, no internal geodynamo is available to drive a magnetic field. Instead, the heat energy from the core is being used to reheat the crust. |
发表于 2012-7-12 15:35:07
