A team of scientists from the University of Wisconsin (USA) has discovered the oldest known fragment of our planet; a 4.4 billion year old piece of zircon . The lump of metal, which is one of the oldest and also most abundant minerals on our planet, was discovered in the Jack Hills area of Western Australia. The discovery has been published in the journal Nature Geoscience .
To determine the age of the fragment, the scientists used two techniques. First, they studied its uranium and lead atoms , since these elements break down over time and their inner imprint can be taken as dating. Second, they used a technique known as atom-probe tomography which, together with secondary ion mass spectrometry, allowed them to pinpoint the age and thermal history of the zircon by determining the mass of the individual lead atoms in the piece of the fragment.
This discovery confirms that zircon crystals from the Western Australia region crystallized 4.4 billion years ago and therefore our planet became habitable for life from that time on with the now confirmed oldest material known on Earth .
This research reinforces the theory that temperatures were low enough to have liquid water, oceans and hydrosphere, shortly after the creation of the Earth's crust (only about 100 million years after the formation of the Earth).
