Planet Earth doesn't have a birth certificate to record its formation, which means scientists spent hundreds of years struggling to determine the age of the planet. So, just how old is Earth? By dating the rocks in Earth's ever-changing crust, as well as the rocks in Earth's neighbors, such as the moon and visiting meteorites, scientists have calculated that Earth is 4.54 billion years old, with an error range of 50 million years.

Scientists have made several attempts to date the planet over the past 400 years. They've attempted to predict the age based on changing sea levels, the time it took for Earth or the sun to cool to present temperatures and the salinity of the ocean. As the dating technology progressed, these methods proved unreliable; for instance, the rise and fall of the ocean was shown to be an ever-changing process rather than a gradually declining one. And in another effort to calculate the age of the planet, scientists turned to the rocks that cover its surface. However, because plate tectonics constantly changes and revamps the crust, the first rocks have long since been recycled, melted down and reformed into new outcrops.

Scientists also must battle an issue called the Great Unconformity, which is where sedimentary layers of rock appear to be missing (at the Grand Canyon, for example, there's 1.2 billion years of rock that can't be found, according to the University of Arizona). There are multiple explanations for this uncomformity; in early 2019, one study suggested that a global ice age caused glaciers to grind into the rock, causing it to disintegrate. Plate tectonics then threw the crushed rock back into the interior of the Earth, removing the old evidence and turning it into new rock. In the early 20th century, scientists refined the process of radiometric dating. Earlier research had shown that isotopes of some radioactive elements decay into other elements at a predictable rate.

By examining the existing elements, scientists can calculate the initial quantity of a radioactive element, and thus how long it took for the elements to decay, allowing them to determine the age of the rock. The oldest rocks on Earth found to date are the Acasta Gneiss in northwestern Canada near the Great Slave Lake, which are 4.03 billion years old. But rocks older than 3.5 billion years can be found on all continents. Greenland boasts the Isua supracrustal rocks (3.7 to 3.8 billion years old), while rocks in Swaziland are 3.4 billion to 3.5 billion years. Samples in Western Australia run 3.4 billion to 3.6 billion years old.

Research groups in Australia found the oldest mineral grains on Earth. These tiny zirconium silicate crystals have awhile that reach 4.3 billion years, making them the oldest terrestrial substances discovered on Earth so far. Their source rocks have no longer but been found. Meanwhile, scientists have additionally observed 7-billion-year-old stardust on Earth.

The rocks and zircons set a lower limit on the age of Earth of 4.3 billion years, due to the fact the planet itself ought to be older than something that lies on its surface.

When existence arose is nonetheless under debate, in particular due to the fact some early fossils can appear as natural rock forms. Some of the earliest types of life have been determined in Western Australia, as announced in a 2018 study; the researchers determined tiny filaments in 3.4-billion-year-old rocks that may want to be fossils. Other research endorse that life originated even earlier. Hematite tubes in volcanic rock in Quebec should have blanketed microbes between 3.77 and 4.29 billion years ago. Researchers looking at rocks in southwestern Greenland additionally noticed cone-like constructions that could have surrounded microbial colonies some 3.7 billion years ago.
More than 70 meteorites that have fallen to Earth have had there a while calculated by radiometric dating. The oldest of these are between 4.4 billion and 4.5 billion years old.

Fifty thousand years ago, a rock hurled down from space to shape Meteor Crater in Arizona. Shards of that asteroid have been accumulated from the crater rim and named for the nearby Canyon Diablo. The Canyon Diablo meteorite is vital because it represents a class of meteorites with aspects that enable for more particular dating.

In 1953, Clair Cameron Patterson, a famed geochemistry at the California Institute of Technology, measured ratios of lead isotopes in samples of the meteorite that put tight constraints on Earth's age. Samples of the meteorite exhibit a spread from 4.53 billion to 4.58 billion years. Scientists interpret this range as the time it took for the solar machine to evolve, a gradual event that took place over about 50 million years.

By the usage of no longer solely the rocks on Earth but additionally data gathered about the gadget that surrounds it, scientists have been in a position to place Earth's age at about 4.54 billion years. For comparison, the Milky Way galaxy that contains the photo voltaic gadget is approximately 13.2 billion years old, whilst the universe itself has been dated to 13.8 billion years.

Conclusion

Loading full article...
Cheers
Gift
Boost
Share to Whatsapp Share to Facebook Share to Pinterest Share to Twitter Share to Telegram Share to LinkedIn Share to Reddit Share with Email