"THE MILKY WAY: AN ELEPHANT IN THE SKY"
Like the three blind men who were said to have touched
different parts of an
elephant and came up with vastly different descriptions, astronomers were
often fooled by ambiguous clues to the nature of the Milky Way. Their
perceptions depended on their research techniques.
J. C. Kapteyn was a statistical astronomer who is often considered the
grand-father of the modern Dutch school of Milky Way astronomy. He built a
model by counting stars of various apparent brightnesses, and although he
understood the potential impact of interstellar extinction of starlight, his
attempts to evaluate it were thwarted by a quirk of nature. He decided to
ignore extinction in his final papers. The result was the "Kapteyn
universe," which has become the primary textbook example of astronomical
research gone astray.
With the hindsight of late 20th century data, this talk will attempt to
understand why Kapteyn made this decision.