The Terrestrial Worlds Physics 112 Star Systems Lecture 13 The Terrestrial Worlds Venus Kevin H Knuth University at Albany Fall 2012

How art thou fallen from heaven, O Lucifer, son of the morning! Isaiah 14:12

Worlds of Rocks and Ice

Venus, Earth and Mars

Comparative Planetology Venus Mass: 4.87 x 1024 kg Diameter: 12,104 km Density: 5.25 gm/cm3 0.72 AU from the Sun Rotation: - 243 days (retro) Revolution: 224.7 days Earth Mass: 5.97 x 1024 kg Diameter: 12,756 km Density: 5.52 gm/cm3 1.0 AU from the Sun Rotation: 1 day Revolution: 365.26 days Mars Mass: 6.42 x 1023 kg Diameter: 6,794 km Density: 3.94 gm/cm3 1.52 AU from the Sun Rotation: 1.03 days Revolution: 687 days

Planetary Interiors crust crust crust mantle mantle mantle solid metallic core solid metallic core molten metallic core molten metallic core Calvin J. Hamilton

Venus

Venus Mass: 4.87 x 1024 kg Diameter: 12,104 km Density: 5.25 gm/cm3 0.72 AU from the Sun Rotation: - 243 days (retro) Revolution: 224.7 days Surface gravity: 8.87 m/s2 Surface Temp: 854° F Atmos. Pressure: 93 atm Atmospheric Composition: CO2 96.5% carbon dioxide N2 3.5% nitrogen Trace amounts of sulfur dioxide, sulfuric acid, water vapor, carbon monoxide, argon, helium, neon, hydrogen chloride, and hydrogen fluoride

Radar Images of Venus A digital composite constructed from images taken by the Magellan space probe.

Radar Images and Maps

No lander has lasted more than an hour on the surface of Venus! Venera 13 (Soviet Mission 1982) No lander has lasted more than an hour on the surface of Venus!

Surface of Venus Venera 13 (Soviet Mission 1982) The soil is basaltic rock intermixed with gravel. It appears to be smoothed by erosion http://www.mentallandscape.com/V_DigitalImages.htm

Surface of Venus Venera Processed Imagery http://www.mentallandscape.com/C_Venera_Perspective.jpg

Venus Map

Venus Volcanic Features The surface of Venus is approximately 300 – 500 years old. Large (greater than 100 km diameter) Large Shield Volcanoes central caldera with many lava flows Intermediate (between 20-100 km) Ticks volcanic domes with radial ridges Pancake Domes circular outlines with relatively flat interiors Calderas and Paterae volcanic depressions with numerous lava flows Small (less than 20 km) Shield Fields Regions with many small domes and volcanic vents http://www.gnewton.ca/fov/archive/venus_volcanic.html

Tick A Tick is a volcanic dome with radial ridges. You can see the volcanic vent with remains of a lava flow in the center of the caldera. This is a radar image taken by the Magellan probe.

Pancake Domes Pancake domes are dome shaped hills with circular outlines. They often occur together and overlap. It is thought that they are due to lava flows that creep out over a relatively flat terrain.

Maat Mons Maat Mons is the highest volcano on Venus. It has a large summit caldera approximately 30 km in diameter.

Maat Mons A recreation of Maat Mons from digital topography data by David P. Anderson

Venus Tectonic Features The crust of Venus is not broken into plates like the Earth’s crust. Tessera (tesserae, pl.) : a terrain network consisting of two or more directions of ridges and troughs. They are tectonically complex terrains, thought to be parts of the crust being pushed together and pulled apart. These are unique to Venus. Chasma (chasmate, pl.) : a broad trench consisting of a parallel arrangement of troughs or valleys bounded by fault scarps. These zones are interpreted to reflect spreading of the crust. Mons (Montes, pl.) : large highland provinces are termed montes descriptive of their mountain range-like appearance. Corona (coronae, pl.) : (mean diameter = 250 km ) are large circular ringed structures with scarps and ridges. Corona are probably formed from deformation of the surface due to mantle upwelling and then depression. Arachnoid(s) : (mean diameter = 115 km ) are circular or elliptical structures that consist of a central dome or depression, surrounded by a network of radial and concentric linear features. These are probably the result of faulting associated with magma injection at shallow depths. Nova (novae, pl.) : (mean diameter = 190 km ) are similar to arachnoids, but are dominated by radial structures. They are associated with uplift and may be the beginning stages of coronae. http://www.gnewton.ca/fov/archive/venus_tectonic.html

Chasma Latorna Corona Dali Chasma Dali Chasma is approximately 625 miles in length. The northern arm of the chasma is bordered by a mountain range rising 1.5 miles with the canyon dropping 1.2 miles.

Tessera Ovda Regio, Venus In the upper left are tessera, composed of criss-crossing valleys. A large caldera can be seen in the lower right. http://www.lpi.usra.edu/publications/slidesets/3dsolarsystem/

Maxwell Montes Maxwell Montes is 12 km high and only 10 km wide at its base. It is extremely steep. A mountain this steep would collapse under its own weight on Earth. However, Venus rock is harder than Earth rock allowing steep mountains like this to exist.

Corona Ovda Regio, Venus This corona has been uplifted and then fell back down. It is associated with volcanic and tectonic activity. Note the circular and radial ridges. http://www.lpi.usra.edu/publications/slidesets/3dsolarsystem/

Corona This is Artemis Corona with a topographic map to show how the structure had upwelled and then collapsed. http://rst.gsfc.nasa.gov/Sect19/Sect19_9.html

Arachnoids corona Arachnoids are circular or oval structures like volcanoes, but they have strange cobweb-like ridges emanating from them. arachnoids

Nova on Yavine Corona This perspective image shows a nova with its star-like features. This nova is situated on a much larger corona.

Impact Craters Craters on Venus are very similar to those on Earth and Mars. However, the high density of the atmosphere limits the range of the ejecta. Golubkna Crater (18.5 miles wide)

Lava-Filled Crater Dickinson Crater which is located on a lava plain seems to have been filled with lava much like the Moon’s crater Tycho. Note again, how the ejecta extent is limited.

Triplets Here are three craters in the Eistla Region. It is possible that the meteorite broke apart before impact especially since they appear to be similarly weathered.

Comparative Planetology Venus Mass: 4.87 x 1024 kg Diameter: 12,104 km Density: 5.25 gm/cm3 0.72 AU from the Sun Rotation: - 243 days (retro) Revolution: 224.7 days Earth Mass: 5.97 x 1024 kg Diameter: 12,756 km Density: 5.52 gm/cm3 1.0 AU from the Sun Rotation: 1 day Revolution: 365.26 days Mars Mass: 6.42 x 1023 kg Diameter: 6,794 km Density: 3.94 gm/cm3 1.52 AU from the Sun Rotation: 1.03 days Revolution: 687 days