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what, how, and when to observe.
For instance, it was through the
gathering and analysis of telescopic
data that the rotation of galaxies
could be measured. This, in turn,
quite unexpectedly led to the
discovery that invisible “dark matter”
must exist. In this way, astronomy’s
contribution to fundamental
physics has been immense.
Astronomy’s scope
Up to the 19th century, astronomers
could only chart the positions and
movements of heavenly bodies.
This led the French philosopher
Auguste Comte to state in 1842
that it would never be possible
to determine the compositions
of planets or stars. Then, some
two decades later, new techniques
for the spectrum analysis of light
began to open up the possibility
of investigating the physical
nature of stars and planets. A new
word was invented to distinguish
this new field from traditional
astronomy: astrophysics.
Astrophysics became just one
of many specialisms in the study
of the universe in the 20th century.
Astrochemistry and astrobiology
are more recent branches. They join
cosmology—the study of the origin
and evolution of the universe as a
whole—and celestial mechanics,
which is the branch of astronomy
concerned with the movement
of bodies, especially in the solar
system. The term “planetary
science” encompasses every
aspect of the study of planets,
including Earth. Solar physics
is another important discipline.Technology and innovation
With the spawning of so many
branches of enquiry connected
with everything in space, including
Earth as a planet, the meaning of
the word “astronomy” has evolved
once again to become the collective
name encompassing the whole of
the study of the universe. However,
one closely related subject does
not come under astronomy: “spacescience.” This is the combination
of technology and practical
applications that blossomed with
the establishment of the “space
age” in the mid-20th century.Collaboration of science
Every space telescope and mission
to explore the worlds of the solar
system makes use of space
science, so sometimes it is hard
to separate it from astronomy.
This is just one example of how
developments in other fields,
especially technology and
mathematics, have been crucial
in propelling astronomy forward.
Astronomers were quick to take
advantage of the invention of
telescopes, photography, novel
ways of detecting radiation,
and digital computing and data
handling, to mention but a few
technological advances. Astronomy
is the epitome of “big science”—a
large-scale scientific collaboration.
Understanding our place in
the universe goes to the heart of
our understanding of ourselves:
the formation of Earth as a life-
supporting planet; the creation of
the chemical building blocks from
which the solar system formed; and
the origin of the universe as a
whole. Astronomy is the means by
which we tackle these big ideas. ■INTRODUCTION
If astronomy teaches
anything, it teaches that
man is but a detail in the
evolution of the universe.
Percival Lowell