Science Forums 2

[HydrogenBond]

One of the reasons water was speculated to come from comets, is comets are also needed to form the earth's supposed iron core. Without comets and because the earth is mostly oxygen as oxides, the iron core would have never phase separated from a starting cloud of ingredients. In other words, if one starts with iron plus oxygen one gets iron oxide. To form metallic iron one needs a reduction potential. Simple gravity will not separate out the iron, only iron oxide would settle in the core, not iron.

An abundance of hydrogen or carbon on the forming earth could provide this reduction potential but the amount of water or CO2 left on the earth should be much higher than observed, since the core is 10,000 times bigger than the oceans. The work around this practical constraint was to use comets to get the iron into the core very quickly before oxidation. The water became a bonus. Now the bonus is not considered correct. Comets for the core remains due to lack of challenging data. It is a theory needed to protect another theory.

Another conceptual problem with the comet theory is that the earth should not have been the only planet or moon formed by comets. There should be far more uniformity in all the rocky planets and their moons. All should have iron cores and all should have water. Venus has plenty of CO2 which is more volatile than water. I guess Venus was bombarded by specialty CO2 containing comets. To assume only the earth was in the path of a particular comet composition is absurd. It really came down to needing fresh absurdity to get politians to cough up resources. The hope was to slip it by common sense long enough to get resources, until data proves otherwise. This allows double the resources to disprove absurdity bringing us back to square one.