I once wrote a story about cute, fuzzy aliens from the planet Dalyna. In order to protect them from earthquakes and volcanoes, I gave their planet a solid mantle and core. No churning, underground magma whatsoever. I thought they’d be happy. Little did I know I was killing them all.
Earth’s mantle is composed of molten rock at temperatures of several hundred to several thousand degrees Celsius and includes a mixture of iron, magnesium, and other metals that remain in a liquid state. This vast, metallic ocean keeps moving because of convection. Warmer material rises to the surface and begins to cool while relatively cooler material sinks and heats up.
Sometimes this movement causes earthquakes and volcanic eruptions, but scientists think it also generates an intense magnetic field. The same magnetic field that makes compasses work.
Meanwhile out in space, the sun is spewing radiation and other dangerous particles, enough to kill every living thing in the Solar System. Fortunately for the people of Earth, these particles are electrically charged and our planet’s magnetic field repels them. The fuzzy aliens of Dalyna, with its solid mantle and therefore no magnetic field… well… they’re dead.
In my defense, I was a kid when I wrote that story, so I didn’t know any better. The lesson for myself and other science fiction writers is this: make sure you’re cool ideas don’t have unintended consequences.
Hirose, Kei. “The Earth’s Missing Ingredient.” Scientific American June 2010. Pages 76-83.
“Mantle (geology).” Wikipedia. http://en.wikipedia.org/wiki/Mantle_(geology).