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Science-Universe: Planets;
Circular domes of Alpha Regio Region on
Venus
Seven circular domes can be seen on the eastern edge of Alpha Regio. They average 25 km (15 mi) in diameter with maximum heights of 750 m (2475 ft). Some scientists believe they are the result of eruptions of thick lava that flowed from a vent on level ground, resulting in an even lateral pattern of lava. The concentric and radial fracture pattern on the surface of thedomes suggests that lava welled up inside the domes, causing the surface to stretch.
Back to Venus
The Planet Venus
Mass (kg)
..................................................................
4.87 x 10^24
Diameter (km)
.........................................................
12104
Mean density (kg/m^3)
.............................................
5250
Escape velocity (m/sec)
............................................
10400
Average distance from Sun (AU)
..............................
0.723
Rotation period (length of day in Earth days)
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243.0 (retrograde)
Revolution period (length of year in Earth days)
........
224.7
Obliquity (tilt of axis degrees)
..................................
178
Orbit inclination (degrees)
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3.39
Orbit eccentricity (deviation from circular)
............
0.007
Mean surface temperature (K)
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726
Visual geometric albedo (reflectivity)
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0.59
Highest point on surface
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Maxwell Montes (17 km above mean planetary radius)
Atmospheric components
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96% carbon dioxide, 3% nitrogen, 0.003% water vapor
Surface materials
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basaltic rock and altered materials