Recently the Planet Four project passed the huge milestone of 4 million image classifications! Citizen scientists on Planet Four classify images of the surface of Mars, taken by the Mars Reconnaissance Orbiter, by marking ‘fans’ and ‘blotches’. Scientists believe that these features indicate wind direction and speed. By tracking ‘fans’ and ‘blotches’ over the course of several Martian years to see how they form, evolve, disappear and reform, we can help planetary scientists better understand the Martian climate. We also hope to find out if these features form in the same spot each year and also learn how they change. Other strange surface features found by Planet Four users include the ‘spiders’ which were featured a previous Daily Zooniverse post.