All professions have their jargon. But astronomy goes the extra parsec. Here’s an example. Vega, one of the brighter stars in the night sky, has an apparent magnitude (i.e., an apparent brightness) of approximately zero. Polaris, the North Star, has an apparent magnitude of about +2. Despite this, Vega appears brighter than Polaris, and not by two, but by a factor of about six times.
References
1.
Arlo Landolt published observations of a large sample of stars in 1983 to serve as standard (calibration) stars. Updates to the Landolt system continue to this day.
2.
Depending on who one talks with, you may find your astronomer using cgs (“centimeter-gram-seconds”) units rather than SI units, so luminosity may be expressed in ergs per second. It’s still all powers of ten, ultimately.
3.
We are making an otherwise-unspoken simplification of absolute magnitude here by only considering brightnesses in visible light. The term astronomers use when considering brightness at all possible wavelengths of light is bolometric magnitude.
4.
To download the activity, see [supplementary material] available under the “References” tab at TPT Online, http://dx.doi.org/10.1119/1.4974133 .
© 2017 American Association of Physics Teachers.
2017
American Association of Physics Teachers
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