Geology of solar terrestrial planets billions of years ago in the cores of massive stars. These elements constituted only 0.6% of the material in the solar nebula. That is why the terrestrial planets could not grow very large and could not exert large pull on hydrogen and helium gas. Also, the faster collisions among particles close to the Sun were more destructive on average. Even if the terrestrial planets had had hydrogen and helium, the Sun would have heated the gases and caused them to escape. Hence, solar terrestrial planets such as Mercury, Venus, Earth, and Mars are dense small worlds composed mostly from 2%
Terraforming of Venus intervention for the purpose of building colossal mountains on Venus to serve as islands of colonization in the skies of Venus. Since Venus only has a fraction of the water on earth (less than half the earth's water content in the atmosphere, and none on the surface), water would have to be introduced either by the aforementioned method of introduction of hydrogen, or from some other extraplanetary source. Paul Birch suggests the possibility of colliding Venus with one of the ice moons from the outer solar systems, thereby bringing in all the water needed for terraformation in one go. This