When writing, it’s best to be specific. Rather than say your setting has a lot of trees, call them elm trees. Rather than mention a bird, mention a pelican. Being specific makes whatever you’re writing about feel more real. It adds detail without making the story longer. For a science fiction writer, being specific means knowing specific things about science. With that in mind, let’s talk about asteroids.
Some asteroids are big. Some are small. They’re rocky and tend to look like potatoes. In fact, some of the asteroids in The Empire Strikes Back are potatoes. But if my characters are going to fly a spaceship into an asteroid field, the scene will be more vivid if I can be specific. Based on my research, I have learned that there are three main types of asteroids.
Carbonaceous asteroids, not surprisingly, contain a lot of carbon. They tend to be darker in color, making them hard to find with a telescope, and look more like giant lumps of coal than potatoes.
Siliceous asteroids, also known as stony asteroids, look more like the ordinary Idaho potatoes you’d buy in the super market. They’re composed of iron and magnesium silicates and are brighter than their carbonaceous cousins.
The third type, the metallic asteroids, have a more variable composition, but usually they have a mixture of iron and nickel. Given their iron content, some might have the reddish coloring of sweet potatoes.
Modern science still has a lot to learn about asteroids, and the only ones available to study are in this solar system. Asteroids in Alpha Centauri might have different compositions. With this in mind, science fiction writers have some freedom to design new asteroid types, perhaps composed of lithium or uranium. The important thing to remember is this: like potatoes, asteroids come in many different flavors.