Martian soil perchlorate readings being caused by terrestrial sources, which at the time were thought could have migrated from the spacecraft either into samples or the instrumentation. However, each new lander has confirmed their presence in the soil locally and the "Mars Odyssey" orbiter confirmed they are spread globally across the entire surface of the planet. While our understanding of Martian soils is extremely rudimentary, their diversity may raise the question of how we might compare them with our Earth-based soils. Applying an Earth-based system is largely debatable but a simple option is to distinguish the (largely) biotic Earth from the abiotic
Fictional planets of the Solar System Fictional planets of the Solar System The fictional portrayal of our Solar System has often included planets, moons, and other celestial objects which do not actually exist in reality. Some of these objects were, at one time, seriously considered as hypothetical planets which were either thought to have been observed, or were hypothesized in order to explain certain celestial phenomena. Often such objects continued to be used in literature long after the hypotheses upon which they were based had been abandoned. Other non-existent Solar System objects used in fiction have been proposed or hypothesized by persons with no scientific standing,