Transcript Sponge: Describe the surface conditions of Venus. Surface Features

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