article_snippet: How did iron become scattered throughout Earth's 2,000-mile (3,200km) thick mantle more than four billion years ago?
article_snippet: That's a question that has puzzled scientists, with most thinking asteroid impacts were the cause, but now a new theory has been presented - iron rain.
article_snippet: By re-analysing the vapourisation point of iron, a study has determined that conditions on early Earth Earth would have caused iron to rain down on the ground.
article_snippet: Scientists in New Mexico New Mexico have a new theory for the origin of Earth's iron.
article_snippet: Research suggests iron would have turned into vapour when meteorites hit early Earth, as shown in the artist's impression above.
article_snippet: Because planetary scientists always thought it was difficult to vapourise iron, planetary scientists never thought of vapourisation as an important process during the formation of Earth and Earth core,' said principal investigator Dr Rick Kraus.
article_snippet: The result of this would have been that a solid piece of iron, after impacting Earth perhaps as part of an asteroid, would disperse into an iron vapour due to the force of the impact.
article_snippet: Forming clouds across the surface, an iron vapour due to the force of the impact would then rain down onto the ground and mix with the mantle, which was molten at the time. '
article_snippet: This changes the way we think of planet formation, in that instead of core formation occurring by iron sinking down to EarthEarth's core in large blobs (technically called diapirs), that iron was vapourised, spread out in a plume over the surface of Earth and rained out as small droplets,' said Dr Kraus. '
article_snippet: The small iron droplets mixed easily with the mantle, which changes our interpretation of the geochemical data our use to date the timing of Earth's core formation.'
article_snippet: This would have happened in Earth's late formative stages more than four billion years ago, with that iron being sent bullet-like into the region between the core and crust - the mantle.
highlights_snippet: Scientists in New Mexico have a new theory for origin on Earth's iron .
  
highlights_snippet: Previously a new theory for origin on Earth's iron was unclear how iron was scattered throughout the mantle .
  