Sponge: Describe the surface conditions of Venus.

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Sponge Describe the surface conditions of Venus.
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Surface Features

• Mostly smooth,
• rolling plains.
• Modest highlands
• and lowlands.

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There are two elevated, continent-sized regions.
They make up only 8 of the total surface area.
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The Ishtar Terra is found in the northern
hemisphere and is about the size of Australia.
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One significant feature of the Ishtar Terra is
the Cleopatra Crater, a volcanic crater that is
100 km across.
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The other elevated region is the Aphrodite Terra.
It is Africa-sized and is located along the
equator.
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Most of the features on Venus are named after
famous women.
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Map projection of Venus showing Ishtar and
Aphrodite Terrae
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Topographical map of Venus showing Ishtar and
Aphrodite Terrae
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Volcanic activityThe most common volcanoes are
shield volcanoes.
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Shield volcanoes are formed when lava wells up
through a hot spot. Many successive lava flows
build up high mountains.
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A caldera (crater) is formed when the lava
recedes.
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The largest structures are coronae. These are
upwellings of mantle material and are structures
unique to Venus.
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Some craters are meteorite impact craters. Some
of these are oddly-shaped probably because the
meteorite broke up in the harsh atmosphere.
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There are no small impact craters. No small
meteorite could make it through the atmosphere to
the surface.
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There is evidence of volcanism today. The levels
of SO2 fluctuate greatly. There are also bursts
of radio energy from the highlands. BUT...
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No erupting volcano has been observed.
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The Soviet landers found the surface to be dry
and dusty.
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The samples of crust tested were of two types

• Basalt - volcanic material formed later in the
  planets history.
• Granite - the original crust material.

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There is no magnetic field, probably due to the
slow rotation rate. This means there is no
magnetosphere, so there is no protection from the
solar wind.
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