English: This image illustrates the eastern Mare Tranquillitatis looking northward as seen by the crew of the Apollo 8 mission. In the upper right of this picture are a pair of features forming hyperbola shapes across the lunar mare. The upper feature is a pair of nearly-joined rilles named the Rimae Cauchy. The southern curve is escarpment Rupes Cauchy. The crater between these two features is the Cauchy crater, for which they are named. To the south of the scarp can be seen a pair of low lunar domes. The dome to the left (west) is the Cauchy Omega (ω) and the other named Cauchy Tau (τ).