In July of 1997, NASA’s Pathfinder mission landed on Mars. The purpose of the mission was to study the geochemistry and magnetic properties of the planet’s rocks and the composition of its atmosphere. This was accomplished by use of a tiny rover robot called “Sojourner,” which traveled across the planet’s surface, studying the rocks up close. Most of the mission’s scientists were geologists, who, being fond of rocks as they were, decided to give names to all the rocks they could see. This included such names as Snoopy, Tigger, and Darth Vader! These labels made it fun and easier to remember which rocks were being referred to over the course of the 83-day mission. A full list of Martian rock names from the Pathfinder mission can be seen at their website here.