Earth dating systems
So, Carbon-14 can only measure things up to just over 50,000 years old, great for determining when someone built a wood fire, but not good for determining the age of a meteorite. It occurs whenever an atom has an unbalanced number of protons and neutrons in its nucleus.The number of protons usually determines the element the atom belongs to and it is fixed for any particular element.On the other hand, the number of neutrons that can be contained in the nucleus can vary.When the number of neutrons is in balance with the number of protons (which does not necessarily means that the number of neutrons has to be exactly the same as the number of protons) then the atoms of a particular element is said to be stable.The amount of time it takes for an unstable isotope to decay is determined statistically by looking at how long it takes for a large number of the same radioactive isotopes to decay to half its original amount.This time is known as the half-life of the radioactive isotope.By studying other planets, we are learning more about our own planet.The effects of impacts and how they might affect us here on Earth, global climate change (Venus vs.
An important point is that we must have an idea of how much of the daughter isotope was in the sample before the decay started.
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.
We have an activity in one of the PSI workshops "Exploring the Terrestrial Planets," that deals with this topic.
So, you can use the radioactive elements to measure the age of rocks and minerals. Their useful range is from about 1/10 their half-life (the time it takes for half of the radioactive element/isotope-- the parent, to convert into a non-radioactive element/isotope-- the daughter) to 10 times their half-life. You can use this to measure the age of a rock from about 128 million years to more than 10 billion years (the Solar System is 4.56 billion years old).