By observing gravitational radiation from a binary black hole merger，the LIGO collaboration has simultaneously opened a new window on the universe and achieved the first direct detection of gravitational waves.Here this discovery is analyzed using concepts from introductory physics.Drawing upon Newtonian mechanics，dimensional considerations，and analogies between gravitational and electromagnetic waves，we are able to explain the principal features of LIGO’s data and make order of magnitude estimates of key parameters of the event by inspection of the data. Our estimates of the black hole masses，the distance to the event，the initial separation of the pair，and the stupendous total amount of energy radiated are all in good agreement with the best fit values of these parameters obtained by the LIGO-VIRGO collaboration