Formation and evolution of the Solar System through further collisions, growing at the rate of centimetres per year over the course of the next few million years. The inner Solar System, the region of the Solar System inside 4 AU, was too warm for volatile molecules like water and methane to condense, so the planetesimals that formed there could only form from compounds with high melting points, such as metals (like iron, nickel, and aluminium) and rocky silicates. These rocky bodies would become the terrestrial planets (Mercury, Venus, Earth, and Mars). These compounds are quite rare in the Universe, comprising only 0.6% of the mass of the
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