[{"command":"openDialog","selector":"#drupal-modal","settings":null,"data":"\u003Cdiv id=\u0022republish_modal_form\u0022\u003E\u003Cform class=\u0022modal-form-example-modal-form ecl-form\u0022 data-drupal-selector=\u0022modal-form-example-modal-form\u0022 action=\u0022\/en\/article\/modal\/7015\u0022 method=\u0022post\u0022 id=\u0022modal-form-example-modal-form\u0022 accept-charset=\u0022UTF-8\u0022\u003E\u003Cp\u003EHorizon articles can be republished for free under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence.\u003C\/p\u003E\n \u003Cp\u003EYou must give appropriate credit. We ask you to do this by:\u003Cbr \/\u003E\n 1) Using the original journalist\u0027s byline\u003Cbr \/\u003E\n 2) Linking back to our original story\u003Cbr \/\u003E\n 3) Using the following text in the footer: This article was originally published in \u003Ca href=\u0027#\u0027\u003EHorizon, the EU Research and Innovation magazine\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003ESee our full republication guidelines \u003Ca href=\u0027\/horizon-magazine\/republish-our-stories\u0027\u003Ehere\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003EHTML for this article, including the attribution and page view counter, is below:\u003C\/p\u003E\u003Cdiv class=\u0022js-form-item form-item js-form-type-textarea form-item-body-content js-form-item-body-content ecl-form-group ecl-form-group--text-area form-no-label ecl-u-mv-m\u0022\u003E\n \n\u003Cdiv\u003E\n \u003Ctextarea data-drupal-selector=\u0022edit-body-content\u0022 aria-describedby=\u0022edit-body-content--description\u0022 id=\u0022edit-body-content\u0022 name=\u0022body_content\u0022 rows=\u00225\u0022 cols=\u002260\u0022 class=\u0022form-textarea ecl-text-area\u0022\u003E\u003Ch2\u003EHow scientists are piecing together the history of the moon\u003C\/h2\u003E\u003Cp\u003EWhat scientists are more certain of is that the two planets became a mass of molten material that gradually cooled to form the Earth and moon.\u003C\/p\u003E\u003Cp\u003E\u2018This molten mass rotated around and formed a disc, which existed for a few days. The temperature, which was very high, cooled slowly and everything heavy coalesced to form the Earth today,\u2019 said \u003Ca href=\u0022http:\/\/perso.ens-lyon.fr\/razvan.caracas\/\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EDr Razvan Caracas,\u003C\/a\u003E a physicist who studies the inside of planets at the French National Centre for Scientific Research in Lyon, France.\u003C\/p\u003E\u003Cp\u003EDr Caracas is running computer simulations of what happened to this mass of atoms and materials immediately after the collision as part of a project called \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/rcn\/205712\/factsheet\/en\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EIMPACT\u003C\/a\u003E. He uses computer power equivalent to 200 desktop PCs running for two weeks to calculate what occurs under one set of conditions after the collision. Three supercomputing centres in France will provide the project\u2019s required 120 million hours of computing time in just five years.\u003C\/p\u003E\u003Cp\u003EThe initial shockwave after the collision of proto-Earth and Theia generated crushing pressures and temperatures perhaps as high as 10,000\u00b0C at the centre.\u0026nbsp;\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u2018It is hard to imagine what conditions were like,\u2019 said Dr Caracas. Almost the entire periodic table of elements would have been in a \u2018super critical condition\u2019 - a fog of disassembled atoms neither in gas nor liquid form.\u003C\/p\u003E\u003Cp\u003EOver the next few days, heavy materials like iron began to form the centre of a new planet - Earth.\u003C\/p\u003E\u003Cp\u003E\u2018The metals would slowly separate as droplets as they cooled, and later the silicates (minerals) would liquify. The heaviest inner part of Earth formed, then material would have fallen down onto the planet,\u2019 Caravas said. \u2018The outer part of the disc would have formed a ring and eventually accrete to form the moon.\u2019\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EClock\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EWhile the Earth came together within days, the moon probably took weeks or months to take shape, according Dr Caracas. There may even have been two moons circling the early Earth, with one crashing into the other to create the moon we see today. Both newly minted bodies then had an ocean of molten rock.\u0026nbsp;\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022https:\/\/research.vu.nl\/en\/persons\/joshua-snape\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EDr Joshua Snape\u003C\/a\u003E, a lunar geologist at VU Amsterdam, the Netherlands, is interested in the early moon. He hopes to determine its age within a range of tens or hundreds of millions of years. The traditional view is that it formed about 4.5 billion years ago.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u2018Something profound was happening on the moon between 4.35 and 4.4 billion years ago. The simplest explanation is that the lunar magma ocean (covering the moon) cooled,\u2019 said Dr Snape.\u003C\/p\u003E\u003Cp\u003EThanks to the moon\u2019s lack of tectonic activity, all of its rocks can tell us about this magma period \u2013 an important stage in the moon\u2019s formation.\u003C\/p\u003E\u003Cp\u003EJust how long the magma took to cool is a crucial question, Dr Snape says. \u2018It is important to understand how long this takes, because we scale up what we know about the moon to other planets.\u2019\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cblockquote class=\u0022tw-text-center tw-text-blue tw-font-bold tw-text-2xl lg:tw-w-1\/2 tw-border-2 tw-border-blue tw-p-12 tw-my-8 lg:tw-m-12 lg:tw--ml-16 tw-float-left\u0022\u003E\n \u003Cspan class=\u0022tw-text-5xl tw-rotate-180\u0022\u003E\u201c\u003C\/span\u003E\n \u003Cp class=\u0022tw-font-serif tw-italic\u0022\u003E\u2018This is why we love the Moon so much. It is a treasure trove, geologically speaking.\u2019\u003C\/p\u003E\n \u003Cfooter\u003E\n \u003Ccite class=\u0022tw-not-italic tw-font-normal tw-text-sm tw-text-black\u0022\u003EDr Joshua Snape,VU Amsterdam, the Netherlands\u003C\/cite\u003E\n \u003C\/footer\u003E\n\u003C\/blockquote\u003E\n\u003C\/p\u003E\u003Cp\u003EAs the moon is the only substantial body in the solar system that we have travelled to and retrieved rocks from, its samples are valuable to scientists. Dr Snape has studied the ratios of isotopes of lead and uranium in rocks returned by the Apollo missions and from lunar meteorites. This ratio acts as a deep-time clock that he has used to calculate when a rock formed.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u2018The moon has a record and acts as a beautiful lab for understanding early planetary processes. This will be applicable to Mars, Mercury or Venus, places that are hard for us to access, and it can even tell us about our own planet,\u2019 said Dr Snape.\u003C\/p\u003E\u003Cp\u003EEarth is not quite so useful because plate tectonics bury and recycle rocks.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u2018This is why we love the moon so much,\u2019 he said. \u2018It is a treasure trove, geologically speaking.\u2019\u003C\/p\u003E\u003Cp\u003EHis studies may be able to reveal, for instance, how long a planetary body remains active with volcanic eruptions when there are no plate tectonics to drive them. This could be important when it comes to studying planets around other stars.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EMagma ocean\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EDr Snape is currently working on a project called \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/rcn\/215242\/factsheet\/en\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EMoonDiff\u003C\/a\u003E that involves trying to recreate rock compositions that existed in the lunar magma ocean. The minerals would not have crystalised immediately but would have done so in a sequence that Dr Snape is now trying to reconstruct.\u0026nbsp; \u0026nbsp;\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EHe crushes and heats the recreated rocks under conditions to match those on the moon when its surface was a molten mass of rock. \u2018This week I\u2019m running experiments at one gigapascal (one billion pascals, a unit of pressure) and 1,200\u00b0C,\u2019 he said.\u003C\/p\u003E\u003Cp\u003EKnowing the sequence that minerals separated out from the magma ocean would help explain the moon\u2019s history and its present geology.\u003C\/p\u003E\u003Cp\u003E\u2018The oldest rocks on the moon (the visible lighter parts) are formed primarily of a mineral called feldspar, which would have floated to the top of the liquid magma ocean,\u2019 said Dr Snape.\u003C\/p\u003E\u003Cp\u003E\u2018On the other hand, that Apollo 12 basalt sample and other rocks like it (which make up the darker grey parts) are formed primarily of minerals that would have been more dense and sunk to the bottom.\u2019\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022http:\/\/lmv.uca.fr\/boyet-maud-2\/\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EDr Maud Boyet\u003C\/a\u003E, a geochemist at the University of Clermont Auvergne, France, studies the Earth\u2019s early molten period and is hoping to pin down when it cooled and first became habitable. To do this, she is examining Earth and lunar rocks as well as meteorites by using new mass spectroscopy techniques among others for a project called \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/rcn\/204463\/factsheet\/en\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EISOREE\u003C\/a\u003E.\u003C\/p\u003E\u003Cp\u003EShe says moon rocks could tell us when the huge collision took place, but to do that we still need to understand the early history of the moon. Rocks from the \u003Ca href=\u0022https:\/\/horizon-magazine.eu\/article\/moon-history-museum-and-we-ve-only-visited-gift-shop.html\u0022\u003Efar side of the moon\u003C\/a\u003E could help.\u003C\/p\u003E\u003Cp\u003ELunar rocks collected during Apollo missions come from the side of the moon facing Earth. The side facing away from us has a difference surface make-up. This could be because the moon underwent a second melting event, perhaps caused by a second massive collision.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u2018We have no samples (gathered) from the far side of the moon,\u2019 Boyet said. \u2018But we have some meteorites (that landed on Earth) that we think came from there.\u2019\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThe research in this article was funded by the EU. 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