Don't quote me on this, it has been a long time since I read the article on Mars, so I'm probably out of date on my information. There is a theory that Mars us

Don't quote me on this, it has been a long time since I read the article on Mars, so I'm probably out of date on my information. There is a theory that Mars used to have plate tectonics, but was hit by a MASSIVE asteroid (around the size of our moon) a long time ago, probably in the southern hemisphere. This is also why Mars has such a huge volcano in the north, almost directly opposite where the asteroid hit. This turned Mars into an egg shaped planet for a while, which caused the core to stop spinning, and stopped its plate tectonics. This is the closest article I could find on this: https://www.scientificamerican.com/article/giant-asteroid-collision-may-have-radically-transformed-mars/ https://www.scientificamerican.com/article/giant-asteroid-co...