In this chapter we will consider several more instances of gravitational lensing, some from point-like masses such as stars and some from extended mass distributions such as galaxy clusters. We will d...In this chapter we will consider several more instances of gravitational lensing, some from point-like masses such as stars and some from extended mass distributions such as galaxy clusters. We will discover that the lensing phenomenon is an important tool for astrophysics. Beyond being an interesting consequence of general relativity in its own right, lensing can provide information about mass that is otherwise unseen, but that still affects the path of light through space.
