An earthquake rattled much of the Northeast on Friday morning, with shaking felt across the New York City metropolitan area and in communities from Baltimore and Philadelphia up through New England.

There are a number of ways to measure the magnitude of an earthquake. Most scales are based on the amplitude of seismic waves recorded on seismometers. These scales account for the distance between ...

The astronomical magnitude system, initially developed by Hipparchus and refined by Ptolemy, quantifies the brightness of celestial objects, with brighter objects having lower magnitudes. Norman R.

Often in these weekly Night Sky columns I refer to the magnitude of a star or planet. The concept of magnitude is relatively easy to grasp. Put simply, magnitude indicates an object’s degree of ...