How do we show that the earth is 4.6 billion years o;d?

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Planet Earth is around 4.6 billion years. As a standard, this is the number the astronomers and other scientists used to work. But where this number 4.6 billion years came from? How do we know? What evidence is there? Captain Astro will tackle this topic with you, and we hope you will understand and also share with others who would like to understand as well. Don't forget to ask questions too.

History controls Earth age.

Before we enter deeply in the topic, let's take a introduction to the history of measuring the age of the earth.

Since the past, in antiques, there are philosophers like Aristotle who have even thought of eternal earth, so it was always there, it will still be there ... lots of debates ... but Christians have come to a limit: 6000 years. .. Debate is harder ... Some Christians try to say that is 6000 in geological, but all do not agree.

It is from the 18th century that the Earth's Age has begun to have a scientific approach. They will begin to analyze sedimentary layers. Will begin with several scientific methods they will try, such as for example the Comte de Buffon's experience, the true name of the Georges-Louis Leclerc, in the XV111th century.

This man observed how sediment was accumulated on the planet, so you can controller how a planet is merged like earth can cool. Well, even though he did not reach accurate results, he had obtained 100,000 years as age, but these experiences contributed to understanding that the earth was older than that history of creation was given.

Discussions are being done constantly on how to control time and age of an object, until the radioactivity phenomenon becomes discovered. At the beginning of the 20th century, a giant man named Ernest Rutherford will develop the radiometric dating technique based on the principles of radioactive disintegration. And in the 1950s, another scientific named Clair Patterson will improve this technique and will succeed in using the Uranium-Plon date method to know the age of a meteorite. And so you will begin to admit that the earth is between 4.5 and 4.6 billion years old.

There, from history to the age of the earth, we understand that there are 2 essential scientific methods used: radiometric datation and study of objects come from space.

Radiometric dating

Let's look at the radiometric datation.

Well, this is a method of radioactive disintegration made on the rock on our planet. It is from some unstable chemical elements in the stone and would transform it into other elements while releasing radiation.

Ask ... We will return to this radiation record for more understanding. They are more used in uranium in the Earth's age method, an element we have studied from school, we remember, in the periodic table, ... Well, what we also call it Mendeleev board.

The rock studied will have a number of uranium and lead, because this disintegration process will allow, for a very long time, uranium transformation into lead. And, it is in measuring the amount of transformation that scientists came to know the age of Earth.

Study objects from within.

Likewise, astronomers can also examine rocks from space, these are meteorites, we know that's rock crossing all the atmosphere of the earth and the residue touch finally our soil. Like the Meteorite 5 Tone Allende that fell on our planet on February 8, 1969 in a small village called Allende, in Mexico.

After all, it is with the Meteorite Allende that a scientific team will bring precision to the earth age thanks to a series of minerals analyzes in 2009, and they find ... listen well ... 4.55 billion input Years.

And, you don't have to ask me why this meteorite is called "Allende". You understand!

Well, in modern time and technology, we can directly look for some pieces of rocks in space: on the Moon, in some asteroids and even on some comets. Because Earth is one of the planets in the solar system, it is the result of the same process that formed it.

Thus the radiometric datation of radioactive disintegration made in these spatial rocks has supported the Earth's age.

Thus the astronomers reach the scientific evidence that the earth, and the entire solar system, is about 4.6 billion years.

Radioactive degradation

Well, now, let's get into the depth of this radioactive degradation.

We are reminded, for a stable chemical element, it must have the same amount of proton and neutral. Then we say it's a stable atom. For example, the stable carbon has 6 protons and 6 neutrons, which is why we call it carbon 12, it is stable, but there are also carbon 14, which has 6 protons and 8 neutrons. Thus it cannot be stable and that is why it gives a radiation we call radioactivity.

Different forms of an atom that still carry the same number of protons and neutrons that may be different, well, so this is called isotope. We understand ... this is the same element but it presents it on several isotopes that can be radioactive or not.

We talk about the radioactivity phenomenon when we are dealing with an unstable isotope. But we must know that there are no isotopic elements that are stable at all in nature. This is the case of uranium, for example. That uranium that you hear about, it has several natural isotopes and all are unstable isotopes, Radioactive Savledi. The 2 main isotopes are Uranium-238 (with 92 protons and 146 neutrons) and Uranium-235 (with 92 protons and 143 neutrons).

We remind you that for a chemical element to be stable, it must have the same number of protons and neutrons. When we say it is a stable atom. For example, the stable Carbon has 6 protons and 6 neutrons, that's why we call it Carbon 12, it is stable, but there is also Carbon 14, which has 6 protons and 8 neutrons. So it cannot be stable and that is why it gives off a ray we call radioactivity.

Different forms of an atom that always carry the same number of protons and the number of neutrons can be different, well, they are called isotopes. We understand...it is the same element but it is presented in several isotopes that may or may not be radioactive.

We talk about the phenomenon of radioactivity when we are dealing with an unstable isotope. But we know that there are elements that do not have stable isotopes at all in nature. It is the case of Uranium, for example. Uranium that you heard, it has several natural isotopes and all are unstable, this means radioactive. The 2 main isotopes are uranium-238 (which has 92 protons and 146 neutrons) and uranium-235 (which has 92 protons and 143 neutrons instead).

Half life

Another concept to understand is the time it takes for the decay to occur, a time that specialists call "half-life" because it is linked to the notion of statistics, because we cannot really predict when exactly a radioactive decay will be completed.

As we have always estimated that the planet has many years old, so let's use a reference that can also have many years also to estimate the age of the Earth. We have seen for example the radioactive isotope Carbon 14.

The half-life is only 5,730 years old, which is the time it takes for half of a sample to disintegrate. Therefore, it is more used to evaluate organic fossils, such as bones and some other tissues from a living being. Uranium half-life is longer, it takes longer for its radioactive decay, a few billion years: 4.5 billion years for Ur-238 and 703.8 million years for Uranium-235. Thus it can be used better for radiometric dating of the planet Earth, or other geological structures in space.

How do geologists do the same for Earth?

When geologists find a piece of rock they estimate to be old, or a piece of meteorite (or a piece of any other object that a spacecraft would bring back to Earth...), they measure the concentration of uranium, thorium, protactinium and lead in it. As they know how and in how much time these bodies disintegrate, they just make a comparison with the number of elements that it contains, this means their concentration in the rock sample; and that's how they came to estimate how much time has passed since that rock was formed. So that's how they got the evidence that the Earth is 4.6 billion years old.

You will also understand that this method is based on statistical principles; this is a method that has some variants linked to the assumption that the sample used is more or less complete, because if, for example, the rock sample has a good part that breaks down a lot, which cannot be strong, you do not have the guarantee of applying quantitative evaluation techniques the remaining stones and those derived from the correct disintegration. Therefore, the results are more in the form of minimum estimates.

Conclusion

In summary, the radioactive dating of uranium rocks is based on measuring how the decay and transformation of uranium isotopes and other products of that rock can yield again. It is by measuring this that we can demonstrate the age of our planet. Remember, this technique can be used on other bodies in our solar system.

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