The first observer to catalog differences in star brightnesses was Greek astronomer Hipparchus. He created a catalog around 135 B.C.E. of roughly 850 stars divided into six ranges. He called the ...

If someone asks you, “How bright is that star?” and your answer is “Pretty bright,” that isn’t very useful. And, of course, it’s worthless for any type of comparative research. So for centuries, ...

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 ...

At least three earthquakes, each stronger than the last, struck Central California on Thanksgiving afternoon with preliminary magnitudes as high as 4.0, according to the U.S. Geological Survey. The ...

Continental transform faults evolve when two plates slide along each other. The most prominent examples are the San Andreas Fault in California and the North Anatolian Fault in Turkey. Earthquakes ...

I.—APPARENT MAGNITUDES: (a) VISUAL.THE magnitude of a star, as determined by direct astronomical observation, is a measure of its apparent brightness on a scale which has been precisely defined only ...

II.—APPARENT MAGNITUDES: (b) PHOTOGRAPHIC. WITH the application of photography to astronomy it was inevitable that attempts should be made to determine apparent magnitudes by photography. Visual ...