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The second planet from the Sun has been known by many names, such as, the mystery planet,
the Evening Star, or the Morning Star. It has been observed since the days of the
early Romans. Since it is so close to the Earth and appears as a very bright light,
it was named Venus after the Roman goddess of love and beauty. Venus stands between
Mercury and our home world, Earth. Its average distance from the Sun is 67.3 million
miles (108.2 million km). The diameter at the equator is 7,520 miles (12,100
km). It is Earth's twin in size. Venus is the fourth smallest planet. It
doesn't have moons or rings.Since Venus is closer to the
Sun than the Earth, it takes only 225 Earth days to orbit the Sun. Venus rotates
very slowly taking 243 Earth days just to rotate one time. On Venus, a day lasts
longer than a year. Another oddity about Venus is it rotates from east to
west. Most planets rotate in the opposite direction. As viewed from Earth,
Venus, just like our Moon, seems to be able to change its shape and distance.
The surface temperature of Venus is incredibly hot. It can
reach 900o F (480o C), day and night.
The reason for the extreme heat is the "greenhouse effect" which exists on the
planet. The atmosphere which is mostly made up of carbon dioxide, accounts for this
phenomenon. Sunlight passes through the atmosphere and heats up the rocky
surface. The rocks radiate heat, but the atmosphere traps the heat not allowing it
to escape into space.
From the mid 1960's to 1981, the Soviet Union launched a number
of Venus space probes to map and land on Venus. In 1980, the Pioneer Venus Orbiter
spacecraft began exploring the surface of Venus for the United States. NASA's
Magellan space probe's mission was to explore the surface of Venus in great detail.
It gathered data covering 98 percent of the planet surface between 1990 and 1994. As a
result of all these probes, we learned that about 70 percent of the surface is a vast
desert of rolling plains; about 20 percent is lowlands; and about 10 percent is
highlands. Two large highlands have been identified. Ishtar Terra is about the
size of Australia. Aphrodite Terra is a region as large as Africa. The Ishtar
Terra region is surrounded by mountains. The largest is known as Maxwell Mountain.
It is an immense volcano. At the summit is a crater nearly 50 miles (80 km)
wide. It rises thousands of feet higher than Mt. Everest which is the tallest
mountain on Earth.
We would expect Venus to be very similar to Earth, given its
close proximity and similar characteristics. Instead, we know that Venus is a
scorching desert, with no oceans and no life. Why is our "sister planet"
so different? Can part of the explanation be the dangerous effect of
"greenhouse warming"?
Venus Facts
| Named for |
.... |
Roman god of love and beauty |
| Mean distance from the Sun |
|
67.3 million miles
(108.2 million km) |
| Length of planet year |
|
225 Earth days |
| Length of planet day |
|
243 Earth days |
| Diameter at Equator |
|
7,520 miles (12,100 km) |
| Main gases in atmosphere |
|
Carbon dioxide |
| Number of moons |
|
0 |
| Number of rings |
|
0 |
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