Earth’s birthday, or rather the age of the old girl, was always known as a ballpark figure and never an exact date, but can now be celebrated due to the discovery and dating of a very old piece of Zircon. The age was determined to be 4.4 Billion years old to be exact. Like the mystique of a lovely older woman whose age is a mystery to the men that seek her attentions, the actual age of this planet has eluded scientists. We’re now much closer to knowing the exact age of the planet, and how life was possible during its formation. Theories about early earth have postulated a variety of scenarios, from the temperatures that were always expected to be hot and cooling down. To now, considered more accurately toward the “Cool Early Earth” theory based in part on the discovery of the Jack Hills Zircon.
Scientists have used ancient mineral grains of Zircon to study the earliest formations of the earth using geochronometers, by measuring the isotopes of Oxygen and lead found on these grains. Evaluations of how the Earths hydrosphere was formed gives a variety of information to researchers that have theorized when life was able to begin, the age of the planet, formation of oceans, and shifts in tectonic plates. Giving rise to more accurate readings. With the discovery of these Zircon formation, the oldest ever found, located in Australia, the Earths birthday can be dated to occurring 160 million years after our own solar system.
Confirming the views of Earth’s earliest temperatures and eventually how it was able to sustain life, spoke John W. Valley, the geochemist on the team that made the discovery. Valley also talked about how this discovery also lends information about the formation of the other planets in our solar system.Valley had stated that these Zircon grains from this find are the oldest formed materials known to man, and piggy-backs the original dating tests that search for lead based isotopes. The manner in which these studies pinpointed in on the date are based on the decay of the lead isotopes. Because the lead isotopes broke down 1 Billion years after the crystals were formed or 3.4 billion years ago, the deposited materials remained in this particular hotspot in Australia. Among the processes Atom-Probe Tomography and Secondary Ion Mass Spectrometry the researchers were able to fully determine the age of the crystal by learning its thermal history and the weight (mass) of the individual lead atoms.
Because of the disparate and varied chemical composition early Earth was bombarded by, the crust was not homogeneous. Only 1 hundred-million years prior to the formation of these Zircon crystals the Earth had been struck by a small planetary body, that resulted in a broken off chunk later becoming our moon, forming an ocean of magma after that melted all of the disparate compounds in the crust. Homogenizing the components with the new injection of iron received by the impact, and later resulting in the crystals that have been discovered. The analogy used to help the layman understand the concept, ‘raisins in a pudding’ stated Valley. The earlier theory was that the lead orientation in these crystals was random and scattered, not clumped as they are in this discovery.
Researchers are using this discovery to fuel other research that will ultimately lead to more accurate dating and information about the planets early formation. For now, scientists can all facetiously say Happy Birthday Earth and celebrate that they can tell the world ever more closely its exact age because of discovering the oldest Zircon crystal known to man.
By Emanuel F. Camacho