04 November 2010 Posted in Crosby Observatory Measuring and
evaluating the brightness of stars can be traced back to the
Greek astronomer and mathematician Hipparchus during 190 - 120
BC. He is responsible for producing a catalogue of comparative
brightness and positioning of over 850 stars. Hipparchus formed
the apparent magnitude scale to determine the brightness of a
star as seen by an observer from earth. How does this scale
work? The brighter the celestial object appears, the lower the
value of its magnitude. For instance, the faintest objects you
can see using the naked eye are indicated with a magnitude of 6,
while the Sun on the apparent magnitude scale is –26.74.
However, most of the stars we gaze at in an urban neighborhood
with our eyes are usually somewhere around 3 to 4 and if using
binoculars, the limit is 10. More recently, through the use of
the powerful Hubble Space Telescope, astronomers have located
stars with magnitudes of 30+. It is this basic classification
from over 2,000 years ago that