Venus
PHYS 178 – 2008 Week 4, Part 1
Venus Colorized Clouds
!
This colorized picture of Venus was taken February 14,
1990, from a distance of almost 1.7 million miles, about 6
days after Galileo's closest approach to the planet. It has
been colorized to a bluish hue to emphasize subtle
contrasts in the cloud markings and to indicate that it
was taken through a violet filter. Features in the sulfuric
acid clouds near the top of the planet's atmosphere are
most prominent in violet and ultraviolet light. This image
shows the east-to- west-trending cloud banding and the
brighter polar hoods familiar from past studies of Venus.
The features are embedded in winds that flow from east
to west at about 230 mph. The smallest features visible
are about 45 miles across. An intriguing filamentary dark
pattern is seen immediately left of the bright region at the
subsolar point (equatorial 'noon'). North is at the top and
the evening terminator is to the left.
PIA00111
2
Table 9-1, p.199
Venus in UV
Venus as Viewed Through Violet and
Near Infrared Filters
These two Galileo images of Venus show
the global structure of cloud patterns at
two different depths in the upper cloud
layers. The large bluish image, taken
through the violet filter, shows patterns at
the very top of Venus' main sulfuric acid
haze layer. The subsolar point is to the
right, not far from the limb; the
atmospheric flow runs to the left from
there. The small red image, taken
through a near infrared filter, shows the
cloud patterns several miles below the
visible cloud tops. The colors shown are
artificial; the images were enhanced at the
National Optical Astronomy
Observatories, Tucson, Arizona.
PIA00073
Figure 9.9 The Surface of
Venus
Views of the
surface of Venus from the
Venera 13 spacecraft. The
upper images show the scene
as recorded by the spacecraft
cameras; everything looks
orange because the thick
atmosphere of Venus
absorbs the bluer colors of
light. Computer processing
has transformed the bottom
images to show what the
scenes would look like under
Earth lighting conditions. The
horizon is visible in the upper
corner of each image.
(USSR Academy of Science
and Carle Pieters, Brown
University)
5
Fig 9-9a, p.202
6
Fig 9-9b, p.202
Figure 9.10 Venus’
Atmosphere
The layers of the
massive atmosphere of
Venus, based on data
from the Pioneer and
Venera entry probes.
Height is measured
along the left axis, the
bottom scale shows
temperatures, and the
red line allows you to
read off the temperature
at each height. Notice
how steeply the
temperature rises below
the clouds thanks to the
planet’s huge
greenhouse effect.
7
Fig 9-10, p.203
Venus topography (Pioneer Venus orbiter)
Hemispheric View of Venus
Centered at 0 Degrees East
Longitude
The hemispheric view of
Venus, as revealed by more
than a decade of radar
investigations culminating in
the 1990-1994 Magellan
mission, is centered at 0
degrees east longitude. The
Magellan spacecraft imaged
more than 98% of Venus at a
resolution of about 100 meters;
the effective resolution of this
image is about 3 km. A mosaic
of the Magellan images (most
with illumination from the west)
forms the image base. Gaps in
the Magellan coverage were
filled with images from the
Earth-based Arecibo radar in a
region centered roughly on 0
degree latitude and longitude,
and with a neutral tone
elsewhere (primarily near the
south pole). The composite
image was processed to
improve contrast and to
emphasize small features, and
was color-coded to represent
elevation. Gaps in the
elevation data from the
Magellan radar altimeter were
filled with altimetry from the
Venera spacecraft and the
U.S. Pioneer Venus missions.
PIA00157
Hemispheric View of Venus
Centered at 180 Degrees
East Longitude
PIA00159
Venus - Golubkina Crater
This image of the Venusian crater Golubkina, a
340 kilometer (20.4 miles) diameter impact
crater located at about 60.5 degrees north
latitude, 287.2 degrees east longitude, contains
Magellan data mosaicked with a Soviet Venera
15/16 radar image of the same feature. The
Magellan part of the image (right) reveals details
of the geology of the crater such as the central
peak, the inner terraced walls, and the extremely
smooth floor of the crater. The smoothness of
the floor may be due to ponding of volcanic lava
flows in the crater floor. The rough, blocky
morphology of the crater ejecta and the sharp
terraced crater wall suggest that this feature is
relatively young. The Soviet data have a
resolution of 102 km (0.601.2 miles); the
Magellan data have a resolution of about 120
meters (400 feet).
PIA00210
3D Perspective of
Golubkina Crater
This three dimensional
representation of brightness
variations in a Magellan radar
image of Golubkina crater
enhances the structural
features of the crater.
Golubkina is 34 kilometers
(20.4 miles) in diameter, and
is located at about 60.5
degrees north latitude, 287.2
degrees east longitude.
Golubkina is characterized by
terraced inner walls and a
central peak, typical of large
impact craters on the Earth,
Moon and Mars. The terraced
inner walls form at late stages
in the formation of an impact
crater, due to collapse of the
initial cavity formed by the
meteorite impact. The central
peak forms due to rebound of
the inner crater floor.
PIA00209
Large Impact Crater in the Eistla Region
This Magellan image shows an impact crater in the central
Eistla Region of the equatorial highlands of Venus. It is
centered at 15 degrees north latitude and 5 degrees east
longitude. The image is 76.8 kilometers (48 miles) wide. The
crater is slightly irregular in planform and approximately 6
kilometers in diameter. The walls appear terraced. Five or six
lobes of radar-bright ejecta radiate up to 13.2 kilometers from
the crater rim. These lobes are up to 3.5 kilometers in width
and form a 'starfish' pattern against the underlying radar-dark
plains. The asymmetric pattern of the ejecta suggests the angle
of impact was oblique. The alignment of two of the ejecta lobes
along fractures in the underlying plains is apparently
coincidental.
PIA00466
Venus - Stein Triplet Crater
The Magellan synthetic
aperture radar (SAR) imaged
this unique 'triplet crater,' or
'crater field' during orbits 418421 on 21 September 1990.
These craters are 14 km, 11
km, and 9 km in diameter,
respectively, and are centered
at latitude -30.1 degrees south
and longitude 345.5 degrees
east. The Magellan Science
Team proposed the name
Stein for this crater field after
the American author, Gertrude
Stein. The crater field was
formed on highly fractured
plains. The impacts generated
a considerable amount of low
viscosity 'flows' thought to
consist largely of shock-melted
target material along with
fragmented debris from the
crater. The three craters
appear to have relatively steep
walls based on the distortion in
the image of the near and far
walls of the craters in the
Magellan radar look direction
(from the left). The flow
deposits from the three craters
extend dominantly to the
northeast (upper right).
PIA00088
Impact Crater Jeanne
This Magellan full-resolution image
shows Jeanne crater, a 19.5 km
diameter impact crater, located at
40.0 degrees north latitude and
331.4 degrees longitude. The
distinctive triangular shape of the
ejecta indicates that the impacting
body probably hit obliquely,
traveling from southwest to
northeast. The crater is surrounded
by dark material of two types. The
dark area on the southwest side of
the crater is covered by smooth
(radar-dark) lava flows which have
a strongly digitate contact with
surrounding brighter flows. The
very dark area on the northeast
side of the crater is probably
covered by smooth material such
as fine-grained sediment. This dark
halo is asymmetric, mimicking the
asymmetric shape of the ejecta
blanket. The dark halo may have
been caused by an atmospheric
shock or pressure wave produced
by the incoming body. Jeanne
crater also displays several outflow
lobes on the northwest side. These
flow-like features may have formed
by fine-grained ejecta transported
by a hot, turbulent flow created by
the arrival of the impacting object.
Alternatively, they may have
formed by flow of impact melt.
PIA00472
Lavinia Region Impact
Craters
Three large meteorite
impact craters, with
diameters that range
from 37 to 50 km, are
seen in this image of the
Lavinia region of Venus.
The image is centered at
27 degrees south latitude
and 339 degrees east
longitude, and covers an
area 550 km wide by
about 500 km long.
Situated in a region of
fractured plains, the
craters show many
features typical of
meteorite impact craters,
including rough (bright)
material around the rim,
terraced inner walls and
central peaks. Numerous
domes, probably caused
by volcanic activity, are
seen in the southeastern
corner of the mosaic.
The domes range in
diameter from 1 to 12
km. Some of the domes
have central pits that are
typical of some types of
volcanoes. North is at the
top of the image.
PIA00214
Fractured Somerville Crater in Beta Regio This Magellan radar image is of a 'half crater' located in the rift between Rhea and
Theia Montes in Beta Regio on Venus. The unnamed crater is 37 km in diameter and has been cut by many fractures or faults since
it was formed by the impact of a large asteroid. The eastern half of the crater was destroyed during the formation of a fault valley that
is up to 20 km wide and apparently quite deep. A north-south profile through the very center of this crater is visible as a result of the
down dropping and removal of the eastern half of the crater. PIA00100
18
Figure 9.6 Pancake-Shaped Volcanoes on Venus These remarkable circular domes,
each about 25 km across and about 2 km tall, are the result of eruptions of highly viscous
(sludgy) lava.(NASA/JPL)
Fig 9-6, p.201
False Color Perspective of Sif and Gula Mons A portion of western Eistla Regio is shown in this three dimensional, computergenerated view of the surface of Venus. The viewpoint is at an elevation of 1.2 km at a location 700 km southeast of Gula Mons, the
volcano on the right horizon. Gula Mons reaches 3 km high and is located around 22 degrees north latitude and 359 degrees east
longitude. Sif Mons, the volcano on the left horizon, has a diameter of 300 km and a height of 2 km. Magellan imaging and altimetry
data are combined to develop a three-dimensional computer view of the planet's surface. Simulated color based on color images
from the Soviet Venera 13 and 14 spacecraft is added to enhance small-scale structure. PIA00200
3D Perspective View of
Gula Mons
The viewpoint is located
110 km southwest of Gula
Mons volcano at the same
elevation as the summit, 3
km above Eistla Regio.
Lava flows extend for
hundreds of kilometers
across the fractured
plains. The view is to the
northeast. Gula Mons is
located at approximately
22 degrees north latitude,
359 degrees east
longitude in western Eistla
Regio. Magellan synthetic
aperture radar data is
combined with radar
altimetry to produce a
three-dimensional map of
the surface. Simulated
color and a digital
elevation map developed
by the U.S. Geological
Survey are used to
enhance small-scale
structure. The simulated
hues are based on color
images recorded by the
Soviet Venera 13 and 14
spacecraft.
PIA00234
Volcanos in Guinevere Planitia
This image, with radar illumination from
west to east, shows three unusual
volcanoes located in the Guinevere
Planitia lowland. At the center of the
image is a large feature (50 km in
diameter) with an unusual shape; very
round when viewed from above with
steep slides and a flat top. These
volcanoes are believed to be the result
of relatively thick and sticky (viscous)
lava flows that originated from a point
source. Although a faint remnant of its
original circular shape is preserved, the
northern rim of this center volcano has
a steep scarp. The scarp is probably the
result of material that has slid away
from the volcano and subsequently has
been covered by lava flows. This
volcano overlaps another feature to the
southwest that is disrupted by many
fractures. The southeastern volcano
appears to be the highest of the three
as its illuminated western edge has the
brightest radar return. The scalloped
edges give this feature a bottlecap- like
appearance. The highly scalloped
edges are probably the result of multiple
material slides along the volcano
margin.
PIA00261
Volcanic Domes on Flank of Volcano Maat
in East Ovda Region
This Magellan image is centered about 3.2
degrees north latitude, 194.9 degrees
longitude in the eastern Ovda region of
Venus. The image, which is 90 km in width
and 80 km in length, shows some small
volcanic domes on the flank of the volcano
Maat. The bright flows to the east are most
likely rough lava flows while the darker flows
to the west are probably smoother flows. The
dark flows do show some roughness,
however, as can be seen by the structure in
the flows to the southwest. These dark flows
also have some debris that has been
deposited on top of the flows. The debris may
be fine material from the surrounding plains
on top of the flow by wind or it may be ash
from the volcano. Small volcanic domes are
very common features on the surface of
Venus, indicating that there has been much
volcanic activity on the surface. Assuming
that the central volcanic cone is symmetrical
in shape and knowing the length of the cone's
side and the incidence angle, radar
foreshortening yields a height and slope of
688 meters and 8.2 degrees, respectively for
the cone. These values are similar to heights
and slopes of some volcanic cones on the
Earth.
PIA00487
Aine Corona
The large circular
structure near the center
of the image,
approximately 200 km in
diameter, is named Aine
Corona. Just north of the
corona is one of the flattopped volcanic 'pancake'
domes thought to have
formed by the eruption of
an extremely viscous lava.
Another pancake dome is
located inside the western
parts of the annulus of the
corona fractures. A set of
small domes iis located
along the southern portion
of the annulus of
fractures. The smooth, flat
region in the center of the
corona is probably a
relatively young lava flow.
The range of volcanic
features associated with
coronae suggests that
volcanism plays a
significant role in their
formation.
PIA00202
Ridges and Cracks
This region of the Lakshmi Plains
on Venus has been fractured by
tectonic forces to produce a
crosshatched grid of cracks and
ridges. Be sure to notice the
fainter linear features that run
perpendicular to the brighter
ones! This image shows a region
40 km across. Lakshmi is a
Hindu goddess of prosperity.
(NASA/JPL)
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Fig 9-8, p.202
The New Solar System ch12
Venus – Executive Summary
• Retrograde spin
– giant impact?
• Atmosphere
–
–
–
–
90 times more massive than earth!s
primarily CO2
clouds: H2SO4 (S from volcanoes)
greenhouse effect: 700 K (450 celsius)
• Surface features
– dominated by 2 continents
– impact craters relatively rare
small craters modified by disintegration/explosion in thick atmosphere
– volcanoes and coronae
– fractures and faults, mountains
tectonic activity; single plate
– crust stronger and less rigid than Earth!s
– surface age < 500 Myr
continuous resurfacing by volcanic activity?
or single catastrophic resurfacing event 500 Myr ago?