Page 283 - NS-2 Textbook

Astronomy

Astronomy is the study of the universe-in particular, today's universe at a temperature greater than 100 tril-
the study of the stars and other heavenly bodies, and lion degrees C.
their composition, motion" position! and size. You might According to this theory, creation began about 13 bil-
ask, "Why delve into the mysteries of the universe? What lion years ago when a huge explosion sent dust and gas
does an astronomer produce or achieve?" The product of hurtling through space in all directions. As this explod-
astronomy is a greater knowledge and understanding of ing fireball expanded, particles destroyed one another,
the universe. True, much of this knowledge has not yet releasing high-energy radiation. Today scientists believe
been used directly. However, the study of astronomy led that this expanding motion will never cease. Indeed,
to the discovery of the fundamental laws governing all studies of the movements of other star groups indicate
modern technology. Astronomy is directly responsible that all are moving away from us at fantastic speeds.
for the scientific age, which has ftmdamentally altered Because of the extremely high temperatures, all the
our lives. matter in this early central core was separated into pro-
The universe is the most awesome concept in the tons, neutrons, and electrons. Just after the explosion,
Iltunan imagination. The size of the tmiverse is beyond however, the temperature dropped enough so that parti-
our comprehension. Earth-based and space-based tele- cles could combine. Elements with high atomic weight
scopes have found 1 million galaxies in the Big Dipper were created when protons captured large numbers of
alone, and they have observed light coming from distant neutrons. But these elements were unstable and qulckly
galaxies and other objects over 12 billion light years decayed into atoms of lesser mass. Slow neutron capture
away. produced more stable elements, with low atomic weight.
This accounts for the high percentage of hydrogen and
helium in the universe and the small amounts of heavier
ORIGIN OF THE UNIVERSE
elements.
There are many theories about the origin of the universe. In May 1992 scientists analyzing data on microwave
Ever since ancient peoples first began to study the world radiation gathered by an orbiting Cosmic Background
around them, scientists and philosophers have won- Explorer (COBE) satellite armounced that they had been
dered how Earth and the universe came to be. Although able to verify the existence of slight temperature varia-
we certainly know more than ancient thinkers did about tions in space that would have resulted from the Big
the origin of things, many questions remain tmanswered. Bang. This discovery has given ftuther support to the
Astronomers and other scientists that speculate on the theory-so much so that several prominent cosmolo-
nature of the universe and try to answer these questions gists called it the greatest scientific discovery of the last
are called cosmologists, and their science is called cos- century.
mology. Cosmologists believe that what is now our solar sys-
The modern scientific theory of the origin of the uni- tem (the Sun, the planets, and their moons) began about
verse is called the "Big Bang," or expanding-universe, 4.5 billion years ago as a large cloud of gas and dust from
theory. It was first proposed in 1927 by the Belgian as- the Big Bang. This cloud consisted of the" cosmic mix" of
tronomer Georges Lemaitre. His theory has since been molecules found everywhere in the universe-90 per-
supported by many other scientists and a growing body cent hydrogen, 9.7 percent helium, and .3 percent heav-
of scientific data. Lema1tre postulated that all matter in ier elements such as carbon, oxygen, iron, and others.
the universe was originally concentrated in an incred- Small eddies developed within the cloud as it turned in
ibly dense mass. Packed inside was all the material of space like a giant whirlpool. A large eddy at the center

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