For example, they don't take into account the gas convecting for hundreds of thousands of kilometers.

例如，他们没有考虑到成百上千千米的气体对流。

The different conditions inside them means the material in them doesn't convect, the hot stuff doesn't rise away from the core.

这意味着它们内部的物质不会对流，热的物质不会从地核上升。

The liquid convects, and this motion generates magnetic fields, similar to the way plasma in the Sun generates magnetic fields.

这些液态物质的对流会产生磁场，类似于太阳中的等离子体产生磁场的方式。