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We have rocks from the Moon brought back , meteorites, and rocks that we know came from Mars. We can then use radioactive age dating in order to date the ages of the surfaces when the rocks first formed, i. We also have meteorites from asteroids and can date them, too.
These are the surfaces that we can get absolute ages for. For the others, one can only use relative age dating such as counting craters in order to estimate the age of the surface and the history of the surface. The biggest assumption is that, to first order, the number of asteroids and comets hitting the Earth and the Moon was the same as for Mercury, Venus, and Mars. There is a lot of evidence that this is true. The bottom line is that the more craters one sees, the older the surface is. This can be interpreted in two ways: Based on our study of meteorites and rocks from the Moon, as well as modeling the formation of planets, it is believed pretty much well-established that all of the objects in the Solar System formed very quickly about 4.
When we age date a planet, we are actually just dating the age of the surface, not the whole planet. We can get absolute ages only if we have rocks from that surface. For others, all we are doing is getting a relative age, using things like the formation of craters and other features on a surface. By studying other planets, we are learning more about our own planet.
How do scientists use radioactive decay to understand Earth's history? | Socratic
The effects of impacts and how they might affect us here on Earth, global climate change Venus vs. Earth and what could happen to Earth in an extreme case, etc. From Wikipedia, radioactive decay is the process in which an unstable atomic nucleus spontaneously loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom element of one type, called the parent nuclide transforming to an atom of a different type another element or another isotope of the same element , named the daughter nuclide.
It is impossible to predict when a given atom will decay, but given a large number of similar atoms, the decay rate on average is predictable.
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This predictable decay is called the half-life of the parent atom, the time it takes for one half of all of the parent atoms to transform into the daughter. This may simply have to do with what the media is talking about. When there is a scientific discussion about the age of, say a meteorite or the Earth, the media just talks about the large numbers and not about the dating technique e. On the other hand, when the media talk about "more recent events," ages that are more comprehendible, such as when early Man built a fire or even how old a painting is or some ancient parchment , then we bring up the dating technique in order to better validate the findings.
Carbon is unreactive with a number of common lab substances: It does burn in oxygen, and if you can pass the combusted gas through limewater, the carbon dioxide will turn the limewater milky by producing calcium carbonate. While not a chemical test, the presence of carbon in a sample like a meteorite can be found by vaporizing the sample and passing it through a mass spectrometer. This is also a way to get at the abundance of the various isotopes of carbon. The isotope doesn't actually deteriorate; it just changes into something else. Isotopes decay at a constant rate known as the half-life.
The half-life is the amount of time it takes for half of the atoms of a specific isotope to decay. Remember, isotopes are variations of elements with a different number of neutrons. The half-life is reliable in dating artifacts because it's not affected by environmental or chemical factors; it does not change. When scientists find a sample, they measure the amount of the original, or parent, isotope and compare it to the amount of the decay product formed. They then count the number of half-lives passed and compute the absolute age of the sample.
Absolute age is just a fancy way of saying definitive or specific age as opposed to the relative age, which only refers to how old or young a substance is in comparison to something else. To illustrate, let's use the isotope uranium, which has a half-life of 4. This means that after approximately 4. If a scientist were to compute this, he or she would say two half-lives went by at a rate of 4. That's a lot of years. So you see, earth scientists are able to use the half-lives of isotopes to date materials back to thousands, millions, and even to billions of years old.
The half-life is so predictable that it is also referred to as an atomic clock. Since all living things contain carbon, carbon is a common radioisotope used primarily to date items that were once living. Carbon has a half-life of approximately 5, years and produces the decay product nitrogen Just as in the example with uranium, scientists are able to determine the age of a sample by using the ratios of the daughter product compared to the parent.
Also, when dating with carbon, scientists compare the amount of carbon to carbon These are both isotopes of the element carbon present in a constant ratio while an organism is living; however, once an organism dies, the ratio of carbon decreases as the isotope deteriorates.
Radiocarbon dating can only be used to date items back to as far as about 50, years old. Radiocarbon dating was used to identify a forged painting based upon the concentrations of carbon detected on the canvas within the atmosphere at the time that the picture was painted. So, to sum this all up, radioactive dating is the process scientists use to conclude the ages of substances dating back several to many years ago by using the isotopes of elements and their half-lives.
What is Radioactive Dating? - Definition & Facts
An isotope is a variation of an element based upon the number of neutrons. The disintegration of the neutrons within the atom of the element's nucleus is what scientists call radioactivity. An isotope disintegrates at a constant rate called the half-life , or the time it takes for half the atoms of a sample to decay. The half-life can also be termed an atomic clock. By counting the number of half-lives and the percentages remaining of parent and daughter isotopes, scientists are able to determine what they call the absolute age of a discovery. Carbon is a specific isotope used in dating materials that were once living.
Other common isotopes used in radioactive dating are uranium, potassium, and iodine. To unlock this lesson you must be a Study. Did you know… We have over college courses that prepare you to earn credit by exam that is accepted by over 1, colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level. To learn more, visit our Earning Credit Page. Not sure what college you want to attend yet? The videos on Study. Students in online learning conditions performed better than those receiving face-to-face instruction.
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Are you still watching? Your next lesson will play in 10 seconds. Add to Add to Add to. Want to watch this again later? Principles of Radiometric Dating. What is Carbon Dating? What is Relative Age? What is Relative Dating? Absolute Time in Geology. Relative Dating with Fossils: Index Fossils as Indicators of Time. Methods of Geological Dating: Numerical and Relative Dating. Major Eons, Eras, Periods and Epochs. Prentice Hall Earth Science: Holt McDougal Earth Science: ScienceFusion Matter and Energy: Discover how scientists determine the age of fossils, rocks, and other geologic phenomena by using the known half-lives of isotopes within each specimen, a technique known as radioactive dating.
Radioactive Dating Ever wonder how scientists concluded the age of the earth to be about 4. Radioactivity Defined Elements occur naturally in the earth, and they can tell us a lot about its past. The Half-Life Isotopes decay at a constant rate known as the half-life. Try it risk-free No obligation, cancel anytime.
Want to learn more? Select a subject to preview related courses: Radiocarbon Dating Since all living things contain carbon, carbon is a common radioisotope used primarily to date items that were once living. Lesson Summary So, to sum this all up, radioactive dating is the process scientists use to conclude the ages of substances dating back several to many years ago by using the isotopes of elements and their half-lives.