Thousands of years ago, early Greek, Egyptian, Babylonian, and Chinese
observers knew of Venus and recorded the planet’s motions.
At Chichen Itza in Central America, the Maya built an observatory
that focused on the points where Venus rose and set on the horizon.
To some, Venus was known as the Morning and Evening Star, and was
commonly thought to be two different heavenly bodies.
With the development of the telescope in the 1600s, astronomers
began to study the planet more closely. By the 1700s, most considered
Venus to be Earth’s "twin," believing that the planet,
which is almost the same size as Earth, was inhabited by humans.
A century later, scientists decided instead that Venus must be warm
and wet; more like the early Earth— swamp-dwelling dinosaurs
and all.
Named
for the Roman goddess of love and beauty, Venus remained a mystery
until the 1900s, when radar imaging and space probes began revealing
a planet as hellish as it was handsome.
Venus is the second planet from the sun, but the hottest in the
solar system. Veiled in clouds of sulfuric acid, its heavy atmosphere
traps solar energy, so temperatures on the planet can get hot enough
to melt lead (900 degrees F/480 degrees C). At the surface, flattened
craters mark two desert continents, and volcanoes rise from giant
plains smoothed by lava flows. Scientists think bright, reflective
areas may be covered in glittering iron pyrite—"fool’s
gold."
In Venus’s carbon-dioxide-rich-atmosphere (deadly to humans),
lightning storms are common, and fierce winds whip around the planet
at high elevations. Gravity is about the same as on Earth, but atmospheric
pressure on Venus is crushing: about 90 times that of Earth’s.
Because Venus rotates so slowly on its axis, a single Venus day
is 243 Earth days long. A patient observer would see the Sun rise
in the west and set in the east, since Venus’s direction of
spin is opposite that of Earth’s. Stranger still, in that
time, more than a year would have passed: A year on Venus is 224.7
Earth days.
Inhospitable as Venus may seem, scientists think the planet might
once have supported life. In fact, some researchers have recently
suggested we could find life there today—microbes hiding high
up in the planet’s acidic cloud cover, where pressure is closer
to Earth’s and water vapor is suspended.
Fortunately, two missions to Venus are now in the works, both designed
to test the planet’s atmosphere. If all goes well, by 2010
we may have tantalizing new information about our forbidding twin.
See Venus as viewed on April 29, 2004, through the 36" refracting
telescope at Lick Observatory.
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