PacSci-Doku: "Relative Measure" Answer

By Dennis Schatz - Senior Vice President for Strategic Programs

The question in this edition is:

What do the measurement of earthquakes and stars have in common?

The answer: Magnitude

Scroll down to see the solution.

Both the severity of earthquakes and the brightness of stars are measured in magnitudes. When these magnitudes were first developed, they were relative measurements. Charles Richter developed the earthquake magnitude scale in the early 1930s. A zero magnitude earthquake was the smallest earthquake that seismographs of that day could detect. Each higher magnitude earthquake is 30 times stronger than the previous magnitude. Thus a 6 magnitude quake is 900 times stronger than a magnitude 4 quake.

The idea of formally ranking stars by their brightness started around the birth of Christ when stars where placed into six different brightnesses - one being the brightest stars and six being the faintest stars that could be seen with the unaided eye in a very dark sky. This was formalized in 1856 by Norman Pogson, who defined a first magnitude star as 100 times brighter than a sixth magnitude star. With the invention of the telescope, we can now "see" much fainter stars, down to at least the 35th magnitude.

Click here and here to learn more about the magnitude of earthquakes. Click here to learn more about the magnitude of stars.

Here is the solution:

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