How to determine the age of a planet

When minerals are formed from magma or lava, they often contain traces of radioactive materials such as uranium. Over time, these radioactive elements decay, meaning they emit radiation, which eventually turns them into new, more stable elements trapped within the mineral.

Consider radioactive uranium-238, a common form of uranium. Its atoms radiate energy until they eventually turn into lead. This process happens at a constant rate known as the half-life, which is the time it takes for half of the atoms to decay. Uranium-238 has a half-life of more than 4 billion years; this is how long it takes for half of the uranium-238 in a sample to turn into lead. This makes it ideal for dating very, very old objects.

Knowing these half-lives, we can calculate the age of the rock based on the ratio of the “parent” radioactive element and the “juvenile” stable element — a method called radiometric dating.

• The mineral zircon is widely used for radiometric dating because it contains relatively large amounts of uranium.
• Uranium lead dating is only one type of radiometric dating.
• Other types use different elements. For example, radiocarbon dating, one of the most common methods, uses a radioactive isotope of carbon that has a half-life of thousands of years and is useful in dating organic matter.

How old is the world?

Using these methods, geologists have found minerals that have reached 1000 years old on Earth. 4.4 billion years, which means that the planet has existed for at least this long. But if scientists claim the world is over 4.5 billion yearsWhere did the extra 100 million years come from?

As mentioned earlier, the Earth has changed a lot over billions of years, particularly due to processes such as plate tectonics, which changed the earth’s crust, giving birth to a new earth from magma, and sinking the old one below the surface of the lithospheric plates. towards the angry “inner” of the planet. As a result, it is difficult to find rocks that were on the surface at the beginning of the planet’s history – they were already eroded or remade into raw materials.

But scientists can use radiometric dating to determine the age of rocks in other parts of the solar system:

• Some meteorites contain material older than 4.56 billion years.
• Rocks from the Moon and Mars date back to approximately the same time, 4.5 billion years ago.

These dates are pretty close to the time when the Solar System began to form from the gas and dust cloud surrounding the newborn star, according to scientists. Knowing all these relative dates, we can begin to create a timeline of how the Earth, Moon, Mars and all the other small pebbles floating in space began to form.