Martian means relating to the planet Mars, or a hypothetical being from Mars. When astronomers study Martian geology, they're examining Mars's rocks, craters, and valleys. When they talk about the Martian atmosphere, they mean the thin layer of gases surrounding that distant red planet.

Since the late 1800s, people have wondered whether intelligent life might exist on Mars. Science fiction writers created stories about Martians, imagining what creatures from Mars might look like and how they might think. H.G. Wells's 1898 novel The War of the Worlds featured hostile Martians invading Earth, while Ray Bradbury's The Martian Chronicles imagined a dying Martian civilization. These stories captured people's imaginations even though scientists now know Mars has no intelligent life.

Today, when someone calls you a Martian, they usually mean you seem strange or out of place, like you're from another planet entirely. A new student struggling to understand inside jokes might feel like a Martian at lunch. The phrase “like I'm from Mars” expresses that feeling of complete confusion about what everyone else seems to understand naturally.

NASA's rovers exploring Mars today are searching for evidence of ancient microbial life, not intelligent Martians, but the word reminds us how long humans have looked at that red dot in the night sky and wondered what secrets it holds.