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A swirling spiral of 100 billion star-suns, star clusters, nebulae,
and cosmic dust, the Milky Way is our Home Galaxy; yet research during the past
ten years has overturned assumptions about even its most fundamental characteristics.
Since 1974, estimates of the radius of the Milky Way have been revised upward
by a factor of three, and estimates of its mass by as much as a factor of ten.
The Milky Way has been elevated to the rank of a major spiral galaxy. Earlier
editions of THE MILKY WAY have conveyed, in an authoritative yet easily understandable
manner, Bart and Priscilla Bok's lifelong fascination with our Galaxy. For two
generations this immensely popular book has been the standard introduction to
the study of the Milky Way. Now -- once again -- scientific advances have demanded
a complete revision and thorough updating. Infrared astronomy, for instance, has
opened a window to the center of the Galaxy, revealing a complex and violent history
and suggesting the existence of a supermassive innermost object -- possibly a
black hole serving as stellar graveyard for hundreds of thousands of in-falling
stars. Infrared has also allowed us to explore the interior of the dark interstellar
clouds that shroud the spiral arms in which most of the new stars of our Galaxy
are formed. And radio astronomy has begun to examine the composition of these
dark clouds, disclosing surprisingly complex molecules, most of them organic.
Recent work has also devised a new model of a galactic corona composed of old
or dying stars, and research into the oldest objects in the Milky Way, the globular
clusters, has exposed puzzling conflicts with estimates of the age of the universe
itself, calling into question current theories of galactic evolution. Burt
J. Bok is Professor of Astronomy, Emeritus, at the University of Arizona. Priscilla
F. Bok, his long-term collaborator, died in 1975. |
