Online Astronomy eText: The Planets
Pictures of Venus
(also see Venera Landers on Venus / The Phases of Venus)
     A visible-light image of Venus, taken by the Pioneer Venus Orbiter in 1979, shows very little variation from a completely white, featureless ball, as Venus' thick atmosphere prevents any view of its surface, even from Venus orbit. (Pioneer Venus Orbiter Team, NASA, image processing by Ricardo Nunes)

     Clouds photographed in the UV by Pioneer Venus Orbiter, at wavelengths strongly absorbed by sulfur compounds in the atmosphere, show patterns in the clouds caused by upper atmospheric winds. Despite the planet's 244 day rotation period, the upper atmospheric winds, like those in the Earth's upper atmosphere, circulate around the planet once every few days. They do not, however, show Hadley or Farrell cells, parallel to the equatorial plane of the planet, due to the near nonexistence of Coriolis effects on the slowly spinning planet. (Pioneer Venus Orbiter Team, NASA, apod970507)

Radar reflectivity map of northern hemisphere (centered on the Venusian North Pole), from Magellan data. Longitude 0 is at the bottom, 90 at the right, 180 at the top, and 270 on the left. The radar images are black (where the surface is smooth, and reflects the radar signal away from the spacecraft) and white (where the surface is rough, and backscatters the radar signal); the color shown is intended to approximate the sky colors from Venera landers, but neither the color nor the brightness or lack thereof is likely to be a true representation of an optical image, if such an image could be obtained. (Credit: SSV, MIPL, Magellan Team, NASA, Planetary Photojournal)

Topographic map centered on the Venusian North Pole. Gaps in the Magellan data were filled in with radar images from the Arecibo telescope. (Credit: NASA/JPL/USGS, Planetary Photojournal)

Radar reflectivity map of southern hemisphere (centered on the Venusian South Pole), from Magellan data. (original image seems to have disappeared from the Web)

Topographic map centered on the Venusian South Pole. Gaps in the Magellan data were filled in with radar images from the Arecibo telescope. (Credit: NASA/JPL/USGS, Planetary Photojournal)

Radar reflectivity map of hemisphere centered on 0 degrees longitude. See the image below for a topographic map of the same region. (Credit: NASA/JPL/USGS, Planetary Photojournal)

Topographic map centered at 0 degrees longitude, and 0 degrees latitude. Gaps in the Magellan data were filled in with radar images from the Arecibo telescope. (Credit: NASA/JPL/USGS, Planetary Photojournal)

Radar reflectivity map of hemisphere centered on 90 degrees longitude. See the image below for a topographic map of the same region. (Credit: NASA/JPL/USGS, Planetary Photojournal)

Topographic map centered at 90 degrees longitude. Gaps in the Magellan data were filled in with radar images from the Arecibo telescope. (Credit: NASA/JPL/USGS, Planetary Photojournal)

Radar reflectivity map of hemisphere centered on 180 degrees longitude. See the image below for a topographic map of the same region. (Credit: NASA/JPL/USGS, Planetary Photojournal)

Topographic map centered at 180 degrees longitude. Gaps in the Magellan data were filled in with radar images from the Arecibo telescope. (Credit: NASA/JPL/USGS, Planetary Photojournal)

Topographic map centered at 270 degrees longitude. Gaps in the Magellan data were filled in with radar images from the Arecibo telescope. (Credit: NASA/JPL/USGS, Planetary Photojournal)

Labeled topographic map of Venus, created from Magellan images. On the left, the Northern hemisphere, and on the right, the Southern hemisphere. (click on image for much larger map; NASA, USGS, Venera 15, Venera 16, Arecibo Imaging Radar, Planetary Photojournal)


Photomosaic of Venus by Magellan

Multiple dome-like volcanoes in shield region of Venus (Niobe Planitia). The domes are mostly about a mile wide and 600 feet high. Some are cut by north-south fractures, indicating that at least some of the crustal deformation postdates the formation of the domes. (Credit and © (commercial use prohibited without permission) NASA, JPL, Calvin Hamilton)

     "Pancake" volcanoes in Alpha Regio region. On the Earth, molten lava pours onto a surface which is ice-cold, in comparison to the temperature of the lava. As a result, a thick solid crust quickly forms, which is difficult for the lava to push forward, causing volcanoes to pile up into fairly steep "cones". On Venus, the much higher surface temperature presumably causes the formation of a thinner crust, which can be more easily pushed forward long distances, so the cone-shaped volcanoes we are familiar with are often replaced by much shallower structures, such as these. (Credits: NASA, JPL, Planetary Photojournal)

     3-D representation of domed/pancake structures created from 1990-94 Magellan orbiter radar data. The image has a strong vertical exaggeration (about five times greater than it would really appear); that is, the structures are much flatter and smoother than shown here. The "pillow" volcanoes are typically 15 miles across, but less than half a mile high. As explained above, this is probably due to the high surface temperatures, which allow lava to flow long distances horizontally, compared to its vertical extent. The cooler temperatures on Earth tend to create steeper, cone-shaped volcanic structures. (Credit: E. De Jong et al. (JPL), MIPL, Magellan Team, NASA, apod100801)

     Approximately 45 mile wide Dickinson impact crater and lava flows created by the heat of the impact, or caused by removal of overburden which kept hot rock below the crater from melting, until it was removed by the impact and explosion which created the crater. Solids ejected by the explosion are piled up around the crater, as on Earth, because of the relatively strong surface gravity; but as in the case of "pancake" volcanoes, the liquids ejected by the crater formation can flow long distances (in this case, well outside the limits of the image). In radar images such as this, bright areas represent "rough" terrain which reflects the side-looking radar back to the spacecraft, while dark regions are "smooth" terrain which acts like a mirror, and reflects the radar energy away from the spacecraft. The actual brightness of the different regions is completely unknown, and an optical image, although showing the same features, would undoubtedly look very different. (Credit: JPL/Magellan/NASA)

     Approximately 43 mile wide Markham impact crater and its lava flows, in an image which shows a much larger area than the one of Dickinson crater, so that the entire "lava" flow is shown. A mixture of ejected debris and lava flowed down a less than 1/10th degree slope for nearly 300 miles, thanks to the high surface temperatures causing minimal fusion crust formation. The diagonal banding in the image is caused by the nature of the side-looking radar data from the Magellan spacecraft. Each orbital pass produced an "image" of a narrow strip parallel to the spacecraft's orbit. Images such as the one above are composites of many such strips. Usually, considerable care is taken to "smooth" the image, and remove any evidence of the original nature of the data; but in this case, a "rough" image was posted, clearly showing the origin of the computer-generated "photomosaic". (Unfortunately, the original image seems to have disappeared from the Web, so no link to it can be provided at this time.)

     Simulated perspective view of Sif and Gula Mons, and a "rift valley" created from Magellan radar images. The cone-like structures seen here are actually almost as flat as the "pancake" volcanoes appear in the exaggerated 3-D image further above. As an example of the exaggeration, Sif Mons, the volcanic structure on the left, is nearly 200 miles across, and only a little over a mile high, which means it is 150 times wide as high; but in the image, it only appears to be about 4 times as wide as high, so there is a vertical exaggeration of nearly 40 times. (Credits: The Magellan Project, JPL, and NASA, Planetary Photojournal)


Above, Maat Mons with 22.5 times vertical exaggeration
Below, Maat Mons in true perspective
     The larger image above is a closeup of the 5-mile-high volcano in the previous image, Maat Mons, as usually presented, with a 22.5 times vertical exaggeration, to show off its structure in detail. The lower image shows the volcano with correct perspective. The loss of detail in the true-perspective image justifies the exaggeration of the other image, but the exaggeration does give an impression of Venus' surface which is much different from reality. (NASA, JPL, Magellan Project, Planetary Photojournal)

Animation showing the (false-color ultraviolet) appearance of Venus' atmosphere, as observed during the approach of the European Space Agency's Venus Express. (ESA/MPS, Katlenburg-Lindau, Germany, apod060717)

Visible (on left) and infrared (on right) appearance of Venus' south pole, as observed by the ESA Venus Express, currently in orbit around Venus. On the left, a visible-light (albeit still false-color) image of the day side of the planet; on the right, extreme contrast and enhancement of an infrared image of the night side reveals vortices in the atmospheric motions surrounding the pole. (VIRTIS, ESA)

The probable structure of Venus. A rocky mantle lies above a metallic core. Temperatures in the interior may be high enough to partially melt the core, but are not high enough to produce convective motions in the core, a magnetic field, or tectonic activity. (portion of image from NASA Multimedia Gallery)