Western United States at Night | International Space Station Scott: "...to those in the western USA. Looks like there's a lot going on down there." Credit: NASA/JSC, U.S. Astronaut Scott Kelly Date: August 10, 2015
Humans are carbon-based life forms, but Earth is not a carbon-based planet. Some scientists think such planets may exist, though, in orbit around distant stars. Cutaway views show a carbon-based planet, possibly made mostly of silicon carbide, or carborundum, compared with the preponderance of oxygen-rich compounds in a silicate planet like Earth. At left is an artist’s view of a carbon-based planet covered in tar, where a meteorite impact has exposed a layer of diamond.