How old is the earth?

How old is the earth? Planet Earth does not have a birth certificate with which we can determine its age, which means that scientists have spent hundreds of years struggling to determine the age of the Earth. Indeed, they did this by determining the age of rocks in the ever-changing Earth’s crust, as well as extraterrestrial rocks, such as the moon and visiting meteors. Scientists have determined that Earth is 4.54 billion years old, with a margin of error of only 50 million years.

Determine the age of rocks

Scientists have made several attempts over the past 400 years to determine the age of the planet. They tried to predict age based on the change in sea levels, and the time it took the earth or the sun to cool down to the current temperature, and also try to predict by the salinity of the oceans.

With the development of age determination techniques, these methods have proven to be unreliable. For example, the rise and fall of ocean levels proved to be an ever-changing process and not a single gradual process!

In another attempt to determine the age of the planet, scientists turned to the study of the rocks that cover its surface. But because tectonic plates are constantly changing and reshaping the Earth’s crust, the first rocks were recycled long ago, so they melted and reshaped into new outcrops.

Scientists must also struggle to solve the Great Unconformity. It might seem that sedimentary layers of rocks are missing, for example, in (Grand Canyon) there are 1.2 billion years of rocks that cannot be found.

In fact, there are multiple explanations for this mismatch. In early 2019, one study suggested that the global ice age had caused glaciers to drift towards rocks, leading to their disintegration, and then the movement of tectonic plates displaced these crumbling rocks towards the Earth’s interior, which led to the removal of old evidence and turning it into new rock. .

In the early 20th century, scientists repeated the radiometric dating process. Previous research showed that isotopes of some radioactive elements decay into other elements at a predictable rate. By examining the elements present, scientists can calculate the initial amount of the radioactive element, and thus the length of time it takes the elements to decay, which allows them to determine the age of the rock.

The oldest rocks on Earth are (Acasta Gneiss), found in northwestern Canada near the “great Slave” lake, which is 4.03 billion years old. But even so, rocks older than 3.5 billion years can be found on all continents.

Greenland boasts the Isua rocks that are between 3.7 and 3.8 billion years old, while the rocks in Swaziland are between 3.4 and 3.5 billion years old. The life span of samples in Western Australia ranges from 3.4 to 3.6 billion years.

A research group in Australia found the oldest mineral grains on Earth. These tiny crystals of “zirconium silicate” have lifetimes of 4.3 billion years, making them the oldest materials ever found on Earth. Its rock source has not been found yet.

In fact, rocks and zircons set a minimum age of 4.3 billion years; Because the planet itself must be older than anything on its surface.

As for the history of the origin of life, it is still being researched, especially since some early fossils could appear as natural rock forms. Some of the oldest life forms have been found in Western Australia, as announced in a 2018 study. Researchers have found tiny filaments in rocks 3.4 billion years old, which could be fossils.

Other studies indicate that life arose earlier. The hematite veins in the volcanic rocks of Quebec may have contained microbes between 3.77 and 4.29 billion years old. Also, when researchers looked at rocks in southern Greenland, they saw conical structures that could have surrounded microbial colonies 3.7 billion years ago.

Evidence from extraterrestrial

In an effort to determine the age of the planet more precisely, scientists are starting to look outside. The material that formed the solar system was a cloud of dust and gas that surrounded the sun in its early days. Then, gravitational interactions combined these materials to form planets and moons, around the same time. By studying other bodies in the solar system, scientists can learn more about the early history of the planet.

The closest thing to the Earth, the Moon, did not take place on its surface as it did on Earth. This means that rocks from early lunar history are still lying on its surface. Lunar samples collected from the Apollo and Luna missions showed that the ages of the rocks ranged between 4.4 and 4.5 billion years, which helped to know more accurately the age of the Earth.

As for how the moon was formed, it is a subject of controversy, while the prevailing theory refers to a collision of a Mars-sized object with the Earth, and then the fragments gathered to form the moon, and other theories indicate that the moon was formed before the earth.

In addition to the large bodies in the solar system, scientists have studied small rocks that fall to Earth. Meteorites come from a variety of sources, some of which come from other planets, after violent collisions tossing matter into space. While others are leftover bits from the early Solar System, they were not large enough to form a compact body.

Although there are no Martian rocks on Earth, samples were present in the form of meteorites that fell on the Earth long ago, which allowed scientists to make rough estimates of the age of rocks on the red planet, and some of these samples date back to 4.5 billion years. It supports other accounts of the early history of planet formation.

There are more than 70 meteorites that have fallen to Earth, whose ages have been calculated by radiometric dating, the oldest of which is between 4.4 and 4.5 billion years old.

50,000 years ago, a rock fell from space and formed a meteor crater in the state of “Arizona”. The fragments of this asteroid were collected from the rim of the crater, which was named after the Canyon Diablo, the nearby abandoned town. The Canyon Diablo meteorite is important because it represents a class of meteorites that contain components that allow a more accurate knowledge of its age.

In 1953, Clair Cameron Patterson, a renowned geochemist at the California Institute of Technology, measured the ratios of lead isotopes in samples of meteorites that set limits for Earth’s age. Meteorite samples show ages from 4.53 to 4.58 billion years.

Scientists interpret this range as the time it took the solar system to evolve gradually over a period of about 50 million years. By studying — not only the rocks on Earth but also the information gathered about the surrounding system — scientists were able to determine the age of the Earth at about 4.54 billion years.

For comparison, the Milky Way galaxy that contains the solar system is roughly 13.2 billion years old, while the universe itself is 13.8 billion years old.




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Aadil Shaikh

Aadil Shaikh

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