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t was a hugely successful
voyage of discovery; an inti–
mate peek at an awesome,
beautiful, yet forbidding world;
a mini solar system in our own
celestial backyard. From nearly half
a billion miles away, the breathtak–
ingly spectacular color photos of Ju–
piter and its moons provided new in–
sights- and raised sorne puzzling
questions-about a giant planet that,
at 1,300 times the volume of Earth, is
almost another star.
Voyager 1, launched from Cape
Canaveral in September 1977, jour–
neyed for 18 months and 400 million
miles before threading its way past
Jupiter and its 13 known moons. At
one point the 1,800-pound spacecraft
carne within 173,000 miles of t he so–
lar system's largest planet. Equipped
with eleven different scientific in–
struments plus special camer as,
Voyager found Jupiter to be sizzling
with powerful radiation and covered
with colorful and violently turbulent
clouds. Over a dozen orange and
white bands were seen rotating in the
ever-changing atmosphere.
The famed Great Red
Spot~sev
eral times the size of Earth- was re–
vealed as a gigantic swirl ing pattern
of deep orange clouds with long
braided flows in shades of tan and
amber streaming away from colossal
pinwheellike spirals and vortices. The
Red Spot, first discovered sorne 300
years ago, appears to be a "perma–
nent hurricane." lndeed, there are
many storms on Jupiter with life–
times so great that by Earth stan–
dards they defy the imagination.
[o, one of the four so-called Gali–
lean satellites discovered by Galileo
in 161
O,
looks like an orange that has
been scarred with an ice pick (see
photo).
lt
has dry salt plains, long
cliffs, dome-shaped features, mesas,
channels, fault Lines and even an ac–
tive volcano! But l o is strangely free
of impact craters, a fact that contin–
ues to puzzle scientists. (Most plan–
ets and moons of the solar system
testify to a time of great meteoric
bombardment in the distant past.
Mars, Venus, Mercury, and the
moon, for example, all show evidence
of extensive bombardment and crat–
ers.) Could the surface of lo have
been created more recently than the
surfaces of other planets and moons?
Speculation abounds that well-estab-
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COIO