How Old is The Earth

There is no definite answer to this question. Since ancient times, people have to figure out the age of the earth, and there are various legends and myths that seem to provide answers. But humans can not think of an answer scientifically until about 400 years ago.


At that time it was proven that the earth revolves around the sun (in other words, the earth is part of our solar system), so scientists know where they should start. To find the age of the earth, they need to know how the solar system was born. How does the sun and all planets?

One theory is called a hypothesis or theory fog ancient origin. According to this theory, one time there had been white-hot gas in very large circles in the sky, and the longer the smaller and more heat. When the gas cloud is getting smaller, he pulled out the ring of gas. Each ring is frozen into planets, and the rest are in the middle of the sun.

Another explanation is called the theory planetasimal. According to this theory, many millions of  years ago, there is a very large mass in the form of small objects and solid-called planetsimal, with the sun at its center. A big star came and pulled the sun, so some sun breaks. These pieces were collected planetasimal a little like a rolling snowball gathering snow and they became planets.


Whichever theory is correct, astronomers think they probably occurred about 5.5 billion years ago! But other scientists than astronomers have been looking for this answer. They try to find the answer by studying how long it takes the earth to reach its present form. They studied the time it takes to become the oldest mountain wear, or the time required to collect sea salt which is now contained in it.

After all their research, scientists agree with the astronomers: age of the earth approximately 5.5 billion years