0kelseymhBest Answer 10 years ago ReplyUpvoteIf you really want a detailed answer to your question (and aren't just a trolling YEC) I strongly encourage you to look up and read some basic undergraduate texts on geology and geophysics. Here are the basics of planetary formation; the question of the origin of life from a complex solution of organic molecules would require a whole separate post of its own. 1) Billions (more than 4.567 billion, specifically), not millions. 2) "Dust" is a generic term used by astronomers for anything larger than individual molecules. The presolar nebula is inferred, from analysis of cometary material and spectroscopic observation of protoplanetary dust disks around other stars, to have contained water, metals, and organic (carbon-containing) compounds both simple -- methane, ethane, acetylene, etc. -- and relatively complex -- formaldehyde, amino acids, polycyclic aromatic hydrocarbons or PAHs. 3) Gravity is a purely attractive force, and is therefore highly conducive to positive feedback. Given a random clumping of material in an otherwise uniform medium, that clump will have (look up the definition of "clump") higher density and therefore slightly high gravity than its surroundings. The clump will therefore suck in nearby material, getting larger. Extend this process of several thousand years, and you end up turning "dust" into asteroids. Keep going, you get planets. 4) Compressive heat and radioactivity. Once you have a self-gravitating body, there will necessarily be a pressure gradient from the center to the surface. As the body accumulates more and more mass, the pressure, and therefore temperature, at the center will increase. Combine this with an accumulation of highly radioactive material -- known to be produced in supernovae and therefore to be constituents of protoplanetary disks -- and you can develop enough temperature to melt the former dust, now rock, at the core of the body.