The planet Venus is a twin sister of our Earth - and as often happens with twins they are similar in form but very different in character. Venus has almost the same mass as Earth, density, chemical composition and internal structure are comparable. However, its nearer to the Sun and this is cause for marked differences: Venus rotates very slowly and retrograde (!). Venus' crust is much thicker than that of Earth, which kept its interior hot but stifled the heat flow to drive convection in the fluid iron core - the most probable reason why Venus does not have an intrinsic global magnetic field and probably never had. Venus has a very dense opaque 90 bar CO₂ atmosphere which experienced a run-away greenhouse effect that caused temperatures to exceed 740 Kelvin - enough to melt lead. Studies of the evolution of Venus atmosphere tell us a lot about the greenhouse effect on Earth. Being nearer to the sun Venus lost most of its water (to space or into a chemical surface sink) and nowadays is very dry. A study of the escape mechanisms at Venus - especially in comparison to Earth and Mars - helps to solve this mystery. The lack of water also explains why the atmospheric CO₂ is not chemically bound to the surface as on Earth and therefore explains the significant surface pressure.

Venus - being the brightest object in the sky besides the Sun and Moon - has been explored by several space probes in the past. Many of them (the Soviet Venera and VEGA series) have carried Austrian instruments to Venus. They also carried landers, which only survived for a few hours in the infernal environment (heat, pressure, acids) of Venus. Other well known Venus spacecraft were the US Pioneer Venus (a long-duration orbiter and 4 hard landers) and Magellan spacecraft (which carried a powerful radar to penetrate the opaque clouds and to map the surface in detail). In Venus Express, the first European mission to Venus, IWF Graz participates as the Principal Investigator institute, providing a magnetometer together with TU Braunschweig and Imperial College London.

Further information on Venus is found at The Nine Planets.