This reveals the main part of the word.
An structural analysis on a word searches for the words that give the words its meaning, the root of a word is from where it comes from, for example, the word methaphysician has two roots meta, which means beyond, and physic which means beyond physics, so a meta physician would be someone that works with things that are beyond physics.
martians or other types of aliens represent a unique fear as opposed to zombies. vampires and other types of monsters. in most sci-fi stories, aliens come from other worlds and have different or more advanced technology. abductions and experimentation on human bodies that involve these technologies, or the use of these technologies against human beings and the use of unknown "powers", are a type of fear that's different from that of other types of monsters.