|How old is the earth?|
|Question Date: 2019-09-06|
The Earth is about 4.56 billion years old, which is when the Earth got to about the current size. Some people may tell you dates that are a bit older or younger because the formation of the Earth took several steps. The Earth first clumped together, but the core of the Earth and the Earth's atmosphere formed later.
Hi Nevaeh, that's a great question! The Earth is roughly 4.56 billion years old. I say roughly because when the Earth first formed, there likely weren't any rocks yet (it was too hot and the planet was basically like a giant magma ocean).
Using a type of science called 'geochronology', geologists can use radioactive elements in rocks and minerals to tell how old they are. The oldest minerals on Earth are the Jack Hills Zircon, from Australia - they are 4.4 billion years old (here's a great website if you'd like to read more about the oldest minerals on our planet: oldest known minerals on Earth ).
Since the first rocks to form on Earth aren't around anymore, we can date the oldest material in the solar system (everything in our solar system formed at about the same time) - these are CAIs, little blebs of melt inside of meteorites that are the oldest, most pristine and original material in our entire solar system. Using geochronology, the CAIs date to ~4.56 billion years old. So, because solar system material is 4.56 billion years old, there's pretty good evidence for the Earth to be that same age (here's a website w/ more info, but it might be hard to understand and you might need your parent/teacher to help you through it: isotopicAges ).
I hope this has answered your question, and that this has piqued your interest in Earth Science! Have a great day!
The Earth is about 4.5 billion years old. A lot of research has been done on the age of the Earth by using meteorites, specifically some of the elements and their different forms in these meteorites. Researchers have used certain meteorites to measure the age of the Earth because these meteorites came from our Solar System and formed around the same time that the Solar System formed. Certain elements in these meteorites break down at fixed rates.
For example, one type of lead, Lead-205, has a half-life of 17.3 million years, which means that if a rock starts with 1 gram of Lead-205 in it, after 17.3 million years, this same rock would end up with 0.5 grams of Lead-205 in it. After another 17.3 million years, or a total of 34.6 million years, the rock would end up with 0.25 grams of Lead-205 in it. Because of this break down process, if we compare two rocks, the rock with less Lead-205 is likely the older one given that the rocks come from similar places and have similar contents in them. By using techniques such as these, scientists have been able to determine that Earth is about 4.5 billion years old.
We don't know exactly, since the processes of erosion destroy rocks on Earth, so no rocks dating from the Earth's formation exist on the planet. However, we currently believe that the moon formed as a result of a collision between the early Earth and another planet, and that the moon formed about 4.5 billion years ago. We also believe, based on element compositions, that the sun is about 4.7 billion years old, and the Earth formed from the same collapsing nebula that formed the sun. This allows us to bracket the age of the Earth: it is older than 4.5 billion years, but younger than 4.7 billion years.
FYI, the oldest rocks on Earth are about 4 billion years old, but some of these formed from other rocks that include mineral grains that are as old as 4.2 billion. Still, these numbers are hundreds of millions of years younger than the known age of the moon, which is a logical lower bound for the Earth's true age.
The Earth is about 4560 million years old. That is 4,560,000,000. 4.56 Billion years.
The way we determine the ages of rocks and minerals is seeing how much of certain elements they contain. Since radioactive elements decay and become other elements at specific rates, if we know the rates, we can tell how old a rock or mineral containing those elements is. The oldest minerals found on Earth are zircon crystals from Australia which are 4.4 billion years old (4,400,000,000 years). This was calculated from the decay of uranium-238 (an isotope of uranium with an atomic mass of 238) to lead-206.
Since Earth's rocks are constantly being recycled, we know that Earth must be older than that. Based on the ages of meteorites that formed in our solar system, we can tell that the solar system and Earth are about 4.5 billion (4,500,000,000) years old.
The earth is around 4.5 billion years old!
Scientists estimate the Earth is 4.5 billion years old! They figured this out by using radiometric dating to determine the age of rocks from the Earth’s crust.
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