he could calculate the distance to the variable stars. Knowing the distance to the stars in a cluster then gave him the distance to the cluster and allowed him to plot where each cluster lies in the Milky Way. These plots showed that the clusters are distributed through a flattened spheroidal volume about 100 kiloparsecs (roughly 300,000 light years) in diameter. They surround a disk of stars in which the Sun lies about two thirds of the way from the center.