-- a program in Special English by the Voice of America.
Richard Rael and Tony Riggs tell the story of American astronomer
Edwin Hubble. He changed our ideas about
and how it developed.
Hubble made his most important discoveries in the nineteen
twenties. Today, other astronomers
continue the work he began. Many of them are using the Hubble space
telescope that is named
Powell Hubble was born in eighteen eighty-nine in Marshfield,
Missouri. He spent his early years in
the state of Kentucky. Then he moved with his family to Chicago,
attended the University of Chicago. He
studied mathematics and
was a good student. He was a good
athlete, too. He was a member
of the University of Chicago championship basketball team in
nineteen-oh-nine. He also was an
excellent boxer. Several people
urged him to train for the world heavyweight boxing championship
after college. Instead, he decided to
continue his studies. He went to Queen's College at Oxford,
Oxford, Hubble studied law. He was
interested in British Common
Law, because his family had come to America from England many years before. He spent three years at Oxford.
nineteen thirteen, Hubble returned to the United States. He opened
a law office in Louisville, Kentucky. After a short time, however,
he decided he did not want to be a lawyer. He returned to
the University of Chicago. There, once
again, he studied astronomy.
watched the night sky with instruments at the university's Yerkes
Observatory. His research involved a
major question astronomers
could not answer: What are nebulae?
astronomical term "nebulae", Hubble explained, had come down through
the centuries. It was the name given to
areas in the sky outside our solar system. Some astronomers
thought nebulae were part of our Milky Way Galaxy. Others
thought they were island universes farther away in space.
his research paper, Hubble said the issue could be decided only
by more powerful instruments. And those
instruments had not yet
nineteen seventeen, the United States was fighting in World War
One in Europe. Edwin Hubble joined the
American army and served
astronomer George Ellery Hale had offered Hubble a position
at the Mount Wilson Observatory in southern California. When
Hubble returned to the United States after World War One, he accepted
Hale's offer. Hubble was thirty years
old. He was just beginning
the work that would make him famous.
his first observations from Mount Wilson, Hubble used a telescope
with a mirror one hundred fifty-two centimeters across. He
studied objects within our own galaxy. And he made an important
discovery about nebulae.
said the light that appeared to come from nebulae really came
from stars near the nebulae. The
nebulae, he said, were clouds
of atoms and dust. They were not hot
enough -- like stars--
to give off light.
after, Hubble began working with a larger and more powerful telescope
at Mount Wilson. Its mirror was two
hundred fifty centimeters
across. It was the most powerful telescope
in the world
for twenty-five years. It had the power
Hubble needed to make
his major discoveries.
nineteen twenty-two on, Edwin Hubble began examining more and
more distant objects. His first great
discovery was made when
he recognized a Cepheid variable star. It was in the outer area
of the great nebula called Andromeda. Cepheid variable stars
are stars whose brightness changes at regular periods.
astronomer at Harvard College, Henrietta Leavitt, had discovered
that these periods of brightness could be used to measure
the star's distance from Earth. Hubble
made the measurements. They showed that the Andromeda nebula lay far outside
our Milky Way Galaxy.
discovery ended a long dispute. He
proved wrong those who
believed nebulae lay inside the Milky Way. And he proved that
nebulae were galaxies themselves. Astronomers now agree that
far distant galaxies do exist.
then began to observe more details about galaxies. He studied
their shape and brightness. By nineteen
twenty-five, he had
made enough observations to say that the universe is organized
into galaxies of many shapes and sizes.
stars differ from one another, he said, so do galaxies. Some are
spiral galaxies like the Milky Way and Andromeda. They have a
center, and arms of matter that seem to circle the center like a
pinwheel. Others are shaped like
baseballs or eggs. A few have
no special shape.
proposed a system to describe galaxies by their shape. His
system still is used today. He also
showed that galaxies are similar
in the kinds of bright objects they contain. All galaxies,
he said, are related to each other, much as members of a
family are related to each other.
the late nineteen twenties, Hubble studied the movement of galaxies
through space. His investigation led to
the most important
astronomical discovery of the Twentieth century -- the expanding
observations about the movement of galaxies had been done by
V. M. Silpher. He discovered that
galaxies are moving away from
Earth at speeds between three hundred kilometers a second and
one thousand eight hundred kilometers a second.
understood the importance of Silpher's findings. He developed
a plan for measuring both the distance and speed of as many
galaxies as possible. With his assistant
at Mount Wilson, Milton
Humason, Hubble measured the movement of galaxies. The two
men did this by studying what Hubble called the "red shift." It
also is known as the "Doppler effect."
Doppler effect explains changes in the length of light waves or
sound waves as they move toward you or away from you. Light waves
from an object speeding away from you will stretch into longer
wavelengths. They appear red. Light waves from an object speeding
toward you will have shorter wavelengths. They appear blue.
of forty-six galaxies showed Hubble that the galaxies
were traveling away from Earth. The
observations also showed
that the speed was linked directly to the galaxies' distance
from Earth. Hubble discovered that the
farther away a galaxy
is, the greater its speed. This
scientific rule is called "Hubble's
discovery meant a major change in our idea of the universe. The
universe had not been quiet and unchanging since the beginning
of time, as many people had thought. It
was expanding. And
that, Hubble said, meant it probably began with an explosion of
unimaginable force. The explosion often
is called "the big bang."
work did not end with this discovery. He
continued to examine
galaxies. He continued to gain new
knowledge about them. Astronomers
from all over the world went to study with him.
left the Mount Wilson Observatory during World War Two. He
did research for the United States War Department. He returned
after the war. Then, he spent much of
his time planning a
new, much larger telescope in southern California. The telescope
was completed in nineteen forty-nine. It
had a mirror five
hundred centimeters across. It was named
after astronomer George
Hubble was the first person to use the Hale Telescope. He died
in nineteen fifty-three while preparing to spend four nights looking
through the telescope at the sky.
work led to new research on the birth of the universe. One
astronomer said scientists have been filling in the details ever
since. And, he said, there is a long way
Special English program was written by Marilyn Rice Christiano. Your narrators were Richard Rael and Tony
again next week for another EXPLORATIONS program on the Voice