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Despite its similarities to Earth in size, mass, density, and possibly composition, Venus has a unique geology that is unlike Earth's. Although much older than Earth's, the surface of Venus is relatively young compared to other terrestrial planets (<500 million years old), possibly due to a global-scale resurfacing event that buried much of the ...
The surface of Venus is comparatively flat. When 93% of the topography was mapped by Pioneer Venus Orbiter, scientists found that the total distance from the lowest point to the highest point on the entire surface was about 13 kilometres (8.1 mi), about the same as the vertical distance between the Earth's ocean floor and the higher summits of the Himalayas.
The similarity in size and density between Venus and Earth suggests that they share a similar internal structure: a core, mantle, and crust. Like that of Earth, the Venusian core is most likely at least partially liquid because the two planets have been cooling at about the same rate, [73] although a completely solid core cannot be ruled out. [74]
It is sometimes called Earth's "sister planet" due to their similar size, gravity, and bulk composition (Venus is both the closest planet to Earth and the planet closest in size to Earth). The surface of Venus is covered by a dense atmosphere and presents clear evidence of former violent volcanic activity.
Venus is similar in size and distance from the sun when compared with Earth, and some researchers believe the planet might have even had an Earth-like climate at some point.
However, this is not because Venus is more volcanically active than Earth, but because its crust is older. Earth's crust is continually recycled by subduction at the boundaries of tectonic plates, and has an average age of about 100 million years, while Venus' surface is estimated to be about 500 million years old. [16]
The lower range used in many definitions of the super-Earth class is 1.9 Earth masses; likewise, sub-Earths range up to the size of Venus (~0.815 Earth masses). An upper limit of 1.5 Earth radii is also considered, given that above 1.5 R 🜨 the average planet density rapidly decreases with increasing radius, indicating these planets have a ...
During three orbit regimes, the surface images were transmitted back to the Earth. These three orbiting motions of the spacecraft are called mapping cycle 1, 2 and 3. During the mapping cycle 1 (left-looking) radar surface mapping on Venus (September 15, 1990 to May 15, 1991), around 70% of the Venusian surface was mapped by synthetic aperture ...