In the exciting, “out of this world” activity described here, students measure the Earth using meter sticks while measuring their shadows in two distant locations. To obtain the size of the Earth, students discover the connection between the measurements of the shadows and a model of the spherical Earth following the method developed by Eratosthenes. In the process, students learned about the history of science and the value of collaborating with students in an international setting, and appreciated the fact that a complex and large object such as our planet can be measured using simple geometric concepts.