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Venus has long been considered Earth’s twin sister. The two planets are very similar in some respects and share many physical and orbital characteristics:

  • inner planets
  • varying terrains on the surface: mountains, plains, high plateux, gorges, volcanoes, crests and impact craters
  • few craters, implying a relatively young surface
  • atmospheres with dense clouds
  • very close chemical compositions
  • closest neighbouring planets

They are born at about the same time in the same cloud of gas and dust, 4.6 billion years ago.

Because of these similarities, we had long thought that below the dense clouds, Venus could be like the Earth and could maybe even harbour life.

But Venus is very different from the Earth in many respects

  Venus Earth Ratio (Venus/Earth)
Mass (1024 kg) 4.8685 5.9736 0.815
Volume (1010 km3) 92.843 108.321 0.857
Equatorial radius (km) 6051.8 6378.1 0.949
Polar radius (km) 6051.8 6356.8 0.952
Volumetric mean radius (km) 6051.8 6371.0 0.950
Ellipticity (Flattening) 0.000 0.00335 0.0

 

  Venus Earth
Number of natural satellites 0 1
Planetary ring system No No
Surface pressure (bar) 92 1.013
Average surface temperature 464 °C 14 °C
Atmospheric composition 96.5% CO2 + 3.5% N2 77%N2 + 21% O2
Topographic range (km) 15 20

 

Detailed comparison between Venus and the Earth
  Venus Earth Ratio (Venus/Earth)
Mean density (kg/m3) 5243 5515 0.951
Surface gravity (eq.) (m/s2) 8.87 9.80 0.905
Surface acceleration (eq.) (m/s2) 8.87 9.78 0.907
Escape velocity (km/s) 10.36 11.19 0.926
GM (x 106 km3/s2) 0.3249 0.3986 0.815
Bond albedo 0.750 0.306 2.45
Visual geometric albedo 0.65 0.367 1.77
Visual magnitude V(1,0) -4.40 -3.86 -
Solar irradiance (W/m2) 2613.9 1367.6 1.911
Black-body temperature (K) 231.7 254.3 0.911
Moment of inertia (I/MR2) 0.33 0.3308 0.998
J2 (x 10-6) 4.458 1082.63 0.004

 

Radar image of the surface of Venus by Magellan. Credits: Magellan Project/NASA/JPL