Dear PF Forum, Why nobody ever thinks of terraforming Venus? Many propose Mars, even as far as Europa (not the continent!) or Titan. Mars has very little atmosphere compared to Earth. Titan has thick atmosphere but too cold. I once read that Carl Sagan proposed the idea by spreading bacterias in upper atmosphere, where the temperature and the pressure are not so high. If I'm not mistaken the equation of photosynthesis is: 6CO2 + 6H2O + Sun light -> C6H12O6 + 6O2 This process will surely eliminate greenhouse gas(CO2) The only problem is that it needs water/hydrogen. But most of the material are there. Sun, CO2. And once the atmosphere is diminished then there's no abundant greenhouse gas, the planet temperature will drop. And the planet are left with many glucose residue on the "soil". Which is suitable for at least insect and other simple organism. After that we can introduce simple plants, algae, moss? All this only involved biology tools, not mechanical tools to convert Venus. Considering that Venus mass is almost like Earth mass and its gravitational pull close to Earth's, it's a suitable planet for habitation. Is this terraforming idea possible? Why nobody ever discuss it? Does the lack of hydrogen/water in the photosynthesis process makes it difficult?