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Tuesday, March 4, 2014

How old is our Earth?

By measuring the age of rocks in the Earth's crust, including Moon rocks and meteorites, scientists calculate the age of the Earth is as old as 4.54 billion years old. Over the last 400 years a number of attempts were made to scientifically calculating the age of the Earth based on sea levels and the time it takes the Earth and the Sun to cool down to the temperature at this time.

As science advances, the method was not reliable so the scientists switched back to the rocks that cover the face of the Earth. The problem is because the tectonic plates of constant change and alter the Earth's crust, the early Earth rocks have been recycled, melted and reshaped into new rock.

In early 20th century, scientists perfected the process of radiometric measurements. Previously scientists found radioactive isotopes of some elements decay into other elements at a level that can be easily predicted.

By studying the elements are there, the scientists could measure the initial quantity of the element and then how long it decays so as to allow scientists to determine the age of rocks it. Earth's oldest rocks found in Canada is Acasta Gneisses near Great Slave Lake. These rocks are 4.03 billion years old.
A fist-size sample of the Acasta Gneisses, rocks in northwest Canada that are the oldest known rocks on Earth. (Picture from: http://www.space.com/)
Rocks older than 3.5 billion years can be found in all continents, such as Supracrustal Isua rocks in Greenland is 3.7 to 3.8 billion years old, Swaziland rocks is 3.4 to 3.5 billion years old, and in Western Australia is 3.4 to 3.6 billion years old. And recently the Researchers in Australia discovered the oldest minerals on Earth, i.e Zirconium silicate crystals is 4.3 billion years old.
A 4.4 billion year old zircon crystal from Australia is the oldest piece of Earth yet found. The source rocks for the small shards have not yet been identified. (Picture from: http://www.space.com/)
In order to improve the calculation of the age of the Earth, the scientists began to switch out the Earth. The materials that make up the Solar System is a cloud of dust and gas that rotation on the young stars. Gravitational interaction has menyatuhkan material to the planets and moons in the same time. By studying other members of the Solar System, scientists can better know the early history of the planet.

Members of the solar system closest to Earth, the moon, is not changed by changes in the landscape that covers the surface of the Earth. To that end, the rock of the early history of the Moon should exist on the Moon. The samples were taken Apollo and Luna missions demonstrated between the ages of 4.4 to 4.5 billion years, and it helped further verify the age of the Earth.

In addition to the members-large members of the solar system, the scientists also studied foreign smaller rocks that fell to Earth. Meteorites come from a number of sources. Some of the other planets after a big collision, some others are chunks of the rest of the early Solar System that expands never great for creating a cohesive form.

Although no data of Martian rocks, the samples in the form of a meteorite that fell to Earth in the past, allowing scientists to estimate the age of Martian rocks. Some of the samples is 4.5 billion years old and the other supporting the estimated age of the early planet formation.

More than 70 meteorites that fell to Earth through radiometric measurements estimated age. The oldest age of 4.4 to 4.5 billion years. 50 thousand years ago, an asteroid struck the Earth to form the Meteor Crater in Arizona. Fractional asteroid crater formed later named Diablo Canyon.

In 1953, Clair Cameron Patterson calculate the ratio of the main isotopes in samples tighten Earth age limit. Meteorite Canyon Diablo meteorite class is important because it illustrates the components that make the Earth become more precise calculations again.

The meteorite samples were between 4.53 to 4.58 billion years. Scientists interpret this range as the time required to evolve the Solar System requires approximately 50 million years. By not only using rocks on Earth but also information collected from the system that surrounds Earth, scientists can ascertain the age of the Earth is 4.54 billion years old. By comparison, the Milky Way is a member of the Solar System 13.2 billion years old, while the universe itself was about 13.8 billion years. (Want to know the age of the Moon?) *** [EKA | FROM VARIOUS SOURCES | SPACE]
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