METEORITES preserved in Antarctic ice are providing baby-snaps of the newly born Earth.
Soon after Earth formed, 4.5 billion years ago, a Mars-sized object smashed into it, chipping off the moon and irrevocably changing the Earth鈥檚 chemical make-up. 鈥淎ll history of primitive materials would have been wiped out as the temperatures soared to above 1500 掳C,鈥� says Michael Lipschutz of Purdue University in West Lafayette, Indiana.
So to find out what Earth was like before then, he examined 29 meteorites from the Antarctic, of the type known as chondrites, which are believed to have formed in the same gas cloud as Earth.
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He analysed them for elements such as cadmium, thallium and indium, which evaporate at high temperatures (Environmental Chemistry, vol 2, p 215). Their concentrations suggest that early Earth was around 500 掳C, which is about 200 掳C cooler than previous estimates.
