how can scientifics determine the age of the earth?
541684
Carbon 14 dating cannot be used to determine the age of the Earth itself.  It has a half-life of only 5730 years, and can only be used on organic materials.  Current techniques can produce accurate results up to about 100 000 years old with Carbon 14, but this is not nearly old enough for the origins of the Earth.\n\nOther methods, such as U-238, or Potassium/Argon (K/Ar) dating can be used on igneous rocks (like volcanic ash, obsidian or granite) to find out when it formed, and have been used to date some of the oldest rocks in the world:  Precambrian granites exposed as part of the Canadian Shield when glaciers scraped all the top layers away during the most recent ice ages (the last of which was a mere 10,000 years ago) have been dated to about 4.2 billion years old, and some Australian zircons have been found to be at least 4.4 billion years old.\n\nHowever even these oldest rocks don't really give us the age of the Earth.  They show us that the Earth must be at least that old, but not exactly when the Earth itself formed.\n\nThe Earth has undergone constant vulcanism and reforming, with oceanic plates sliding under continental plates and being melted and reformed, and even continental plates dividing, subducting, transforming, eroding and being buried under new lava flows.  The oldest ocean beds are Triassic in age, perhaps a mere 300 million years old or less.\n\nHowever meteorites have not undergone this same reworking.  Presumably, most of them would have been formed at the dawn of the solar system, as the sun and planets were accreting from the gas cloud into more solid, spinning forms.  A meteorite from Canyon Diablo has been used as the sort of benchmark test, it is a very large metallic nickel-iron meteorite with sulfide materials, and ideal for most forms of radiometric dating.\n\nThe Canyon Diablo meteorite comes out to 4.567 billion years old.  Other extra-terrestrial rocks, such as the moon rocks, Mars rocks, and other meteorites come out to about the same ages, between 4.53 to 4.58 billion years old.  This range has been determined through a number of different techniques on a wide number of different samples, and they always come out in the same range, thus indicating that it probably accurate.\n\nSo the age of the Earth is generally taken to be about 4.5 to 4.6 billion years.
776734
It's called radio-carbon dating.\nhttp://en.wikipedia.org/wiki/Radio-carbon_dating
1140994
I like your spirit. Keep it up!!\n\nAfter reading a few of the answers I can't help but break out in laughter. Is this 2006? or is it before Renaissance?\nMight I mention a few things: radio carbon dating, cosmic background radiation, speed of light, distance of some galaxies from us, the time to form heavy elements from hydrogen, half life of uranium...\nI think any one of these things will prove the age of the earth. Incidentally, the Hindu scriptures, Vedas are about 6000 years old. The last ice age ended 13000 years ago...\n\nI can't believe these same people boast about space travel. LMFAO.\n\nIncidentally for the person who said something about matter and energy. No matter and energy can't be created or destroyed. Matter and energy are actually the same thing in different forms. One is a more stable form, the other is a transient form.\n\nAnd the person who said the Bible is the truth. Well the bible didn't arrive by fax from heaven. It was written by men. The laws of physics, on the other hand, was written by God. Scientists merely discover them.
254077
How is the mass of the Earth determined? Newton, Galileo, Henry Cavendish, and Eratosthenes contributed to this amazing calculation. \n\n\nThis calculation is done using Newton's Law of Gravity, which formulates the attractive force (gravitational force) that two masses exert on each other: \n\nF=GmM/r2 \n\nIn Newton's equation, F is the gravitational force, G is a constant of proportionality, M and m are the two masses exerting the forces, and r is the distance between the two objects. \nG was calculated by Henry Cavendish in 1798, and was determined to be 6.67 x 10-11 m3/(kg sec2). \nAlso needed is Newton's second law of motion, F=ma, where F is the force applied to an object, m is the mass of the object, and a is its acceleration due to the force. \nGalileo determined that the acceleration due to the force of gravity of Earth was a constant equal to 9.8 m/sec2 near the surface of the Earth. \nLastly, you need to know the radius of the Earth; this was first calculated by the Greek Eratosthenes thousands of years ago (by comparing shadows in wells during the summer solstice about 230 B.C.). \n\n\nCALCULATING THE MASS OF THE EARTH\n\n1. F = GmM/r2 = ma, where F is the gravitational force, G is the gravitational constant, M is the mass of the Earth, r is the radius of the Earth, and m is the mass of another object (near the surface of the Earth). \n\n2. GM/r2= a (The m's canceled out.) Now solve for M, the mass of the Earth. \n\n3. M = ar2/G, where a=9.8m/sec2, r=6.4 x 10 6m, and G=6.67 x 10-11m3/(kg sec2). \n\n4. M = 9.8 x (6.7 x 106)2/6.7 x 10-11 = 6.0 x 1024 kg
66159
The generally accepted age for the Earth and the rest of the solar system is about 4.55 billion years. I am not an expert on this matter, but I believe in science. If someday people find new convincing theories, I will be very open to accept them. But only 6000 years old? Come on, I don't buy it.
572825
Estimate 1: The best age for the Earth, 4.54 billion years old, is based on old, presumed single-stage leads coupled with the Pb ratios in troilite from iron meteorites, specifically the Canyon Diablo meteorite. In addition, mineral grains (zircon) with U-Pb ages of 4.4 Ga have recently been reported from sedimentary rocks in west-central Australia.\n\nEstimate 2: 4.6 billion years (4,600,000,000 years)\nRadiometric dating (Uranium, Thorium). Mass spectrometer.\n\nSee sources in links. I'm going to guess in-between those two measurements at about 4,570,000,000 years old.
1156152
There was a Bishop Ussher who, by following the time line of the Bible genealogies, determined that the earth to be about 10,000 years of age.  What you are taught in school is a point of interest.  The age of rocks are determined by the types of bones found in them.  The age of the bones by the rocks they are found in.  Who was there in the beginning in order to give the first age.  Modern ages are all guesses.  Yours is probably better than theirs - can't be worse.
1049902
The official answer is that the rock itself dates clear back to the precambrian. That is OLD, somewhere between 700 and 4700 million years ago.
976654
Looking at astoriods because the whole solar system was formed from the same stuff and the rocked in the Earth is being renewed by subduction a creation zones so you can never tell how old that rock is because it will have been remade many times since the formation of the Earth.\n Radioactive dating not the most accurate but radioactive particles are in everything and they all decay so you can tell how old something is by looking at how much the radioactive particles have decayed \nalso there is carbon dating. You have to set things on fire for this so obviously you cnt do this on everything so it's not terribly accurate \nALSO I'M ONLY 12 YEARS OLD
7880
How Old Is The Earth, And How Do We Know?\n he generally accepted age for the Earth and the rest of the solar system is about 4.55 billion years (plus or minus about 1%). This value is derived from several different lines of evidence.
765931
When?\n\nThere are at least 3 ways that the age of the Universe can be estimated. \n\n    * The age of the chemical elements.\n    * The age of the oldest star clusters.\n    * The age of the oldest white dwarf stars. \n\nThe age of the Universe can also be estimated from a cosmological model based on the Hubble constant and the densities of matter and dark energy. This model-based age is currently 13.7 +/- 0.2 billion years. The actual age measurements are consistent with the model-based age which increases our confidence in the Big Bang model.\n\nHow?\n\nNo one really know for sure how however by taking in consideration the evidence the closest thing on how our universe was formed is the Big Bang model. \n\n“Our universe began in a hot dense state which began, and still is expanding. In this initial event, all the matter in our universe was created with approximately 80% hydrogen and 20% helium.”\n\nSome will say what about god? The Big Bang, like all science, doesn’t have any implications either for or against God. What it may do, it place constraints on how God did things and these may run contrary to scripture.
153391
I'm assuming that that refers to giving the age of two things relative to one another, rather than identifying the absolute ages of things.  For instance, when you take two trees that lived in similar times and places, you can look at the width of the tree rings to get an idea as to the conditions (especially moisture) during a given year.  If you have two such wood samples, you should be able to see a pattern between the two.  Using taht information, you could count rings and figure out how much older one piece of wood was relative to the other.  But without knowing the year the trees dies, or without knowing the particular calendar years behind the droughts, you wouldn't know that absolute age of either.  I'd imagine that there are similar things with radioisotope dating if you have a reason to think that the atmospheric conditions creating certain isotopes might change, but not knowing the exact concentrations at the time an organism lived.
968818
Shanna and Geo06 have got this just about right.  The only thing I can add is that radiocarbon dating can not be used for more than about 70,000 years ago, and is more accurate for living things that died within the last 8,000 years.\n\nMost geologists measure rock ages in millions, or even billions, of years, so the age of the earth and the age of almost all igneous rocks is well beyond the range of carbon dating.  On top of that, igneous rocks contain very little if any carbon,  so carbon dating is not applicable here.  \n\nSo the only thing carbon 14 can be used for is to determine the time that an exchange of carbon with the atmosphere stopped, ie, the death of a living thing - the third item on your list of choices for your homework.\n\nThe half life of C-14, the radioactive isotope of carbon, is about 5730 years.  Therefore, if you know the ratio between C-14 and C-12 in the atmosphere when the organism died, and you know the ratio now, the difference in the ratio can be calculated backwards, using the half life, to estimate when the organism died. \n\nAtmospheric C-14 has not been in a constant ratio with C-12, as previously thought, so there are some serious problems with the accuracy of C-14 dating.  The problem is that the natural ratio of the carbon isotopes in the atmosphere (carbon dioxide) varies because cosmic ray bombardment of the outer atmosphere produces C-14 but not C-12.  The ratio can be predicted accurately using the ratios in old trees, where the tree rings can be used to accurately determine the age of each ring with its annual ratio, with a maximum of about 8,000 years -that's how old the oldest trees are which can establish a reference ratio.\n\nDating of artifacts is a best guess, the best method is to measure the amount of lichens growing on them, or the age of carbon in ashes found in the same spot.
85861
~4.5 Billion years old.
525263
Most of what people examine when they look at earth history is the different life forms that occurred in the past.\n\nHowever, there is more to earth history than just fossils. We just need to look at things that are inorganic rather than organic in nature.\n\nStratigraphy is one way to examine earth's history. We can look at the way sedimentary rock has been deposited to tell alot about former environments. We can find out about transgressions & regressions of the oceans & other changes in sedimentary environments.\n\nOxygen isotopes can be used to determine past climates. Speleothems are analyzed for the oxygen isotopes. They are usually looking for heavy isotopes of oxygen. Heavier isotopes of oxygen tend to get locked up in ice sooner than "normal" oxygen. So if a speleothem has less heavy oxygen then we know the sea level was probably lower due to it being "locked up" in the icecaps. This would tell us a lot about how much the sea has risen & how much of the polar ice caps had melted, etc. By the way, speleothems are cave deposits usually referred to as stalactites & stalagmites.\n\nWe can also look at ice cores from Antarctica & the Arctic. They are also examined for isotopes of oxygen.\n\nWe can look at tree rings for not too distant reaches into the past.\n\nVarves are subtle layers that have been laid down at the bottom of lakes or ponds that show changes in environment. This works much like tree rings.\n\nCores from the ocean floor are also used & works in much the same way as varves except on a larger scale.\n\nAs far as radiocarbon dating goes, it is only useful on things that were once living b/c all living things build up carbon as they live. When they die, these radioactive carbon isotopes begin to break down steadily over time.\n\nHowever, there are other radioactive isotopes that can be used to find out the ages of rocks. It works on the same principle as radiocarbon dating; radioactive isotopes break down at a constant & steady rate which soley depends on their half-life of that particular isotope.\n\nSome of the other radiometric isotopes used to date rocks are: Potassium/Argon & Uranium/Lead
396602
4.5 billion years old maybe http://www.talkorigins.org/faqs/faq-age-of-earth.html
587794
There are actually many ways to date the rocks. One well-known way is carbon-dating.\n\nOne great site is:\nhttp://archserve.id.ucsb.edu/Anth3/Courseware/Chronology/01_Contents.html\n\nThis site has short summaries for each method-- no need to read a scientific journal artical for each method.