Do the planets ever get smaller by melting and erosion?
Melting and erosion must occur on other planets. For instance, Mars has ice caps, and the surface shows channels where water or something once flowed. Also we see dust storms. But do planets get smaller? I don't think so. Think about Earth — ice may melt and rocks erode, but that just moves stuff (water, sand) around on the surface. To make the planet get smaller, stuff would actually have to leave the planet! Gravity makes sure that it doesn't. Is there pollution on any of the planets? By pollution, we usually mean something man-made that doesn't belong there. I guess you could say that we have polluted the moon, Mars, and Venus, because we sent satellites and probes to them and just left them there when we were done with them! Hopefully when the astronauts visited the moon, they cleaned up their Coke cans and orange peels before they flew back to Earth. Have scientists found any microscopic organisms that live on any (other) planet? The only place we have looked thoroughly i
