Richter magnitude scale O. Wood and John A. Anderson developed the Wood-Anderson seismograph, one of the first practical instruments for recording seismic waves. Wood then built, under the auspices of the California Institute of Technology and the Carnegie Institute, a network of seismographs stretching across Southern California. He also recruited the young and unknown Charles Richter to measure the seismograms and locate the earthquakes generating the seismic waves. In 1931 Kiyoo Wadati showed how he had measured, for several strong earthquakes in Japan, the amplitude of the shaking observed at various distances from the epicenter. He then plotted the logarithm of the amplitude
Absolute magnitude and a difference of n magnitudes in absolute magnitude corresponds to a luminosity ratio of 100. For example, a star of absolute magnitude M=3 would be 100 times more luminous than a star of absolute magnitude M=8 as measured in the V filter band. The Sun has absolute magnitude M=+4.83. Highly luminous objects can have negative absolute magnitudes: for example, the Milky Way galaxy has an absolute B magnitude of about −20.8. An object's absolute bolometric magnitude represents its total luminosity over all wavelengths, rather than in a single filter band, as expressed on a logarithmic magnitude scale. To convert