How Old is The Earth?

Age of Earth Cover

Our planet is truly a wonderful place to be and perhaps the only place to be in the universe as we have yet to find life on other planets. We have observed that each and every creature that is born on this planet must one day die as well and in between these two points, life happens. Aging is one fact that cannot be halted and each living organism ages, which makes us question how old exactly is Earth? You might be surprised to know.

What is Earth’s age?

While humans have pondered a lot on the age of our planet in the past, we now have scientific data that shows that our Earth is approximately 4.54 billion years old, and on the grander scheme of things, it is fairly new, as the Big Bang that set everything into action occurred 13.8 billion years ago. However, finding the age of Earth wasn’t a simple task as it had puzzled many for thousands of years. To accurately determine the age of Earth, researchers studied ancient rocks and not only from Earth but also from the moon as well along with meteorites.

Radioactive decay

An illustration of radioactive decay.

In addition to that, it didn’t help that Earth had undergone various changes during its formation which led to even more confusion and complications. Radiometric dating is used in order to determine the age of rocks, in this traces of radioactive impurities are monitored and compared to naturally occurring radioactive isotopes and see their decay. After such complex calculations and measurements, we got to know the age of our planet. Not long ago, in the mid-1800s, it was said that our planet is about 400 million years old, which as we know now is quite inaccurate.

How Earth came to be

Though now we know how old our planet is, when the Earth was formed it was nothing like today, and it was a planet that would’ve instantly killed any creature that lived on it. So how it transformed from such a hostile place to our green planet of today? Let’s take a look and while talking about the formation of Earth, time is generally split into four segments of eons; Hadean, Archean, Proterozoic, and Phanerozoic. Also, each eon represents a billion years but the measurement is done in mya (million years ago).

Solar system formation Earth age

Formation of planets in the solar system.

According to scientists, when our Sun was formed it was not as bright but was still dense and had the same mass and due to this, gravity began ruling a set region of space which later became our solar system. Prior to this, a supernova had taken place and debris was all over and gradually this debris started clumping together thanks to gravity, and slowly larger chunks of material from space were gathered and that is how various planets of our solar system were formed. But let’s get back to Earth, once it took shape, that is from where we begin counting its age.

  • Hadean: This started from 4,540 mya and during this time Earth was a molten ball of rock, literally. Heavier elements like iron and nickel sank into the center of the Earth due to immense gravity and having no atmosphere it was constantly bombarded with radiation and asteroids and finally, after thousands of years as the Earth’s surface was exposed to the vacuum of space it began cooling down and a crust began to form, but it was short-lived. At around 4,000 mya a proto-planet collided with Earth and turned it into what can only be described as hell, with rocks melting, hot material spewing onto the surface and into space. Earth started to appear more like Saturn at this point with debris encircling it but due to this cataclysmic event, the moon was born and slowly it got locked into its orbit, and due to the moon profound change started appearing on Earth, an atmosphere of toxic gases was formed.
  • Archean: From the previous Era’s ending to 2500 mya, this eon is known as Archean Eon. After the atmosphere was formed, even though it was toxic it sheltered Earth from radiation and space rocks which led to Earth having the first form of life, these were tiny microbes and interestingly enough their fossils can still be found. Similar to today Nitrogen was the dominant gas in the atmosphere, however, it made up over 90% of the atmosphere and reacted with iron-rich oceans resulting in surreal green seas. At this point, tiny bacteria are known as cyanobacteria began emerging and these were responsible for the vital gas, oxygen, these started photosynthesizes with carbon dioxide and sunlight and release oxygen. So much so that within 200 thousand years, oxygen was so abundant that it started oxidizing the oceans. Finally, the ice age took over, and most life forms were dead.
  • Proterozoic: As the ice started to melt, it gave birth to the first organisms that had a nuclear membrane around their DNA, these were known as Eukaryotes. Now since the planet was covered in ice, no gases were present and there was no atmosphere yet again and life was still in the ocean. But as we know that before the ice age, oxygen was abundant it started to rise upwards as the snow started to melt and by reacting with ultraviolet rays, Earth finally got its protective ozone layer. Near the end of this eon, complex life was present in the oceans and few arachnids and plants on the land.
  • Phanerozoic: Now since oceans were getting crowded with complex life forms, slowly some creatures began evolving to be able to breathe onto the surface, and slowly but surely our planet began transforming as these creatures stepped out of the water and began existed on the surface. From here on, life boomed on the surface and diversified quickly and Earth underwent many changes in its atmospheric composition to cater to new species. Finally, the asteroid came and disrupted Earth yet again and that is how we came to be.
Human Earth Age

Present life on Earth.

The bottom line is that Earth has undergone so many changes in order to cater to new living creatures. Even though it is almost 4.6 billion years old, life is still a new and rare concept in the universe.

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