Thousands of scientists and protesters are expected to rally in Washington, D.C., and other cities around the country Saturday for the March for Science. Assembling on Earth Day, the March for Science organizers and the Earth Day Network will gather at the National Mall in Washington, D.C., for speeches and programs before marching through the streets of the nation’s capital. Mona Hanna-Attisha, the pediatrician responsible for exposing the water crisis in Flint, Mich., will speak at the rally, along with science educator Bill Nye (of Bill Nye the Science Guy). Similar events will take place in other cities around the world, including Los Angeles, New York City and Chicago, among others.