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January 2002 --
Credit: Conrad Jung
From when it was first observed through a telescope, the
planet Saturn has given a unique experience to observers.
Its magnificent system of rings, originally described as
“jug handles” and thought to be a pair of moons, were later
identified as objects that circled, but did not touch, the
planet. Over 280,000 kilometers in diameter, a single
kilometer thick, and made of billions of pieces of ice
ranging from house-sized to dust grains, Saturn’s ring
system has ever been a thing of beauty and mystery.
Credit: Conrad Jung
February 10, 2006 - Credit: Conrad
Jung
Credit: Conrad Jung
Credit: Carter Roberts
December 2000 - Credit: Conrad
Jung
A Brief Observational History of
Saturn
Galileo was the
first to observe Saturn through a telescope—and what he saw
confused him. He described seeing knobs, or “jug handles,”
sticking out on either side of the planet’s disk—features
that would periodically vanish from view. In 1655,
Christiaan Huygens figured out what was happening: Saturn’s
unique feature was a system of rings surrounding, but
nowhere touching, the planet itself. The vanishing act
happened when these rings—which had to be very thin, Huygens
reasoned—turned edge on as seen from Earth.
Using a more powerful telescope
than Galileo or Huygens had, Jean Dominique Cassini
discovered a new feature of Saturn, in the rings themselves:
a dark “gap” separating what had previously been seen as a
single wide ring. This gap, called the “Cassini Division,”
is a dark section of the rings 4700 kilometer wide—the width
of the United States, coast to coast.
From the first photograph of Saturn
in 1883 onward, more and more details of the Ringed Planet
were observed, including additional thin rings and ring
“gaps,” light spots on Saturn itself, and an ever-increasing
count of Saturnian moons. Saturn’s rotation period, or day,
was measured, as well as the periods of revolution of the
different parts of Saturn’s ring, which were found to vary
at different distances from the planet.
Today, the Hubble Space telescope
has shown us tiny details in the cloud patterns of Saturn’s
atmosphere, as well as lightning discharges, auroras,
storms, and extremely high speed winds. Even more moons have
been discovered, and fine, thin bands, in the hundreds, are
revealed in the rings.
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