Earth may have started as dust in the wind. Unlike in many other stellar systems we鈥檝e seen, the area close to our sun is empty. That may be because early in the solar system鈥檚 formation, the solar wind blew聽rocks near the sun into the area where Mercury, Venus, and Earth eventually formed.
The solar wind is a stream of particles聽emanating from the sun. Right now, the sun blows out almost 40 million billion kilograms of material a year, but this gale may have been even stronger in the past. If that is the case, then the solar wind may have played a crucial part in the formation of the innermost planets.
Christopher Spalding at Yale University used simulations of the early sun鈥檚 wind to determine how it would affect any rocks within the current orbit of Mercury. We already think that rocks in the area were small, rather than planet-sized, because Jupiter probably聽migrated through the nascent solar system, breaking up any would-be worlds growing near the sun.
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One-two punch
He found that any rocks with diameters around 100 metres or smaller would likely be pushed away from the sun into the regions where Mercury, Earth, and Venus were forming, where they may have acted as building blocks for these rocky worlds. 鈥淚t鈥檚 this one-two punch of Jupiter coming in and the solar wind finishing the job,鈥� says Spalding.
The findings rely on the assumption that the early solar wind was much stronger than it is today because the sun was more active and spinning faster. 鈥淚f the wind was strong, this effect will be there, but if it was not strong then it will not,鈥� says Ofer Cohen at the University of Massachusetts Lowell. We don鈥檛 have enough information about the early sun to tell,聽he says.
Read more: Moon water blew in on solar wind
If the solar wind was strong enough to blow boulders, though, it could account for some strange findings in Earth鈥檚 interior and also in some of the oldest rocks in the solar system, both of which show evidence of having once been much hotter than their current distances from the sun can account for.
鈥淭his may have been material that was once closer in than Mercury and was getting blasted by the sun鈥檚 heat,鈥� says Spalding. 鈥淚t still records this history of being hot even though it鈥檚 in a colder place today.鈥�
Reference:
Since this article was first published,聽Ofer Cohen鈥檚 academic affiliation has been corrected.
