There are enough similarities between Earth and Venus that many scientists consider the two to be near twin planets that happened to evolve in different directions. Below is a chart showing the characteristics of Venus compared to Earth attributes.
|Diameter||12,742 km||12,100 km|
|Mass||5.9736×1024kg||4.868 x1024 kg|
|Surface Gravity||9.78 m/s2||8.87m/s2|
|Surface Area||510,072,000 km2||460,000,000 km2|
|Surface Atmospheric Pressure||92 times that of Earth|
|Average Surface Temperature||14 degrees Celsius||462 degrees Celsius|
Venus compared to Earth shows a planet of extremes. Yes, a few physical characteristics are similar, but there are many more differences. Looking at the chart above you can see how the temperature and atmospheric pressure would combine to crush your smoldering body. Add to that the sulfuric acid clouds and droplets and you can see how human exploration of the planet’s surface is not in the immediate plans of any space agency.
In fact, everything that is known about the planet’s surface has been gained through radar observation. The atmosphere is amazingly thick and highly reflective. Over 60% of the Sun’s visible light is reflected off the atmosphere, preventing observation. Through radar astronomy from Earth and orbit, scientists know there are over 1,000 volcanic craters or remnants over 20 km in diameter on the surface. Images also show the surface is nearly covered in lava flows. The planet may have been completely resurfaced by lava between 300 and 500 million years ago.
Like Earth, Venus has a magnetic field. It is much weaker and is not created in the same way. Earth’s magnetic field is created internally by the movement of the planetary core and convection from the same area. On Venus it seems to be created by the interaction of the ionosphere and the solar wind. Venus appears to have a liquid core that rotates like Earth’s, but can not move heat through convection because the surface is too encrusted by volcanic rock.
The characteristics of Venus compared to Earth show a few similarities. A few scientist grasp at straws to show a comparative relationship between the two. As you can see, there are far more differences to be explored. In 2014 and 2016 BepiColombo and Akatsuki will have their chances to do just that.
We have also recorded a whole episode of Astronomy Cast that’s just about planet Venus. Listen to it here, Episode 50: Venus.