The maiden second generation (2G) detector is expected to start taking data in a few years from now. Other LIGO and Virgo detectors of that class will join in the following years. Together they will pave the way for direct detections of gravitational wave (GW) signals and plant the first steps in GW astronomy. In the first part of the talk I will describe the type of sources they will target and the problems we are working on now to enable their detection.
The construction of third generation (3G) detectors will likely happen after the first successes of 2G detectors. That has, however, not stopped some of us from envisaging the maximal GW science potential that may be realizable with an earth-based detector within a decade of the advent of the 2G detectors. The 3G detectors will be ten times more sensitive and will hear signals down to as low as 1Hz, rather than 10-15Hz in their 2G predecessors. They will shed light on the equation of state of neutron stars and, perhaps, tell us why pulsars glitch. If they detect intermediate mass binary black holes they will likely unravel what kind of environments seeded their formation. They will also probe the equation of state of the dark energy, independent of supernova Type Ia observations. In the second part of my talk I will discuss the GW sources that 3G detectors will observe and the astrophysics they will teach us.