What is the age of our "Earth"? How to arrive to that figure?
396602
4.5 billion years old maybe http://www.talkorigins.org/faqs/faq-age-of-earth.html
180148
4.3 years older than it looks now.\n\n300 million years.\n\nJust a baby!
527301
Difficult to say for certain. Some possibilities include:\n\nSwallowed up as the Sun enters red giant stage\nYou will need: patience\n\nMethod: Simply wait for roughly 5,000,000,000 years. During its natural progress along the Main Sequence, the Sun will exhaust its initial reserves of hydrogen fuel and expand into a red giant star - swallowing up Mercury, Venus, Earth and Mars in the process.\n\nEarth's final resting place: Boiling red iron in the heart of the Sun.\n\nFeasibility rating: 8/10. The problem here is that current scientific theories predict the Earth will probably survive. The increasing solar wind combined with the Sun's decreasing mass will result in the Earth gradually moving out to a wider, cooler, safer orbit.\n\nEarliest feasible completion date: AD 5,000,000,000\n\nTorn a new one\nYou will need: about half as much patience\n\nMethod: Recent experimental results seem to show that the expansion of the universe is not slowing as one might imagine it would. In fact, the expansion is accelerating. It's a bit early to say with confidence why this is happening, though phrases like "dark matter" and "phantom energy" pop up pretty frequently, but anyway, it's conjectured that if the ratio w of dark energy pressure to dark energy density in the universe is negative enough (buh?), then the universe would expand, accelerating in its expansion until it was ripped apart at the seams. To quote Wikipedia's entry: "First the galaxies would be separated from each other, then gravity would be too weak to hold individual galaxies together. Approximately three months before the end, solar systems will be gravitationally unbound. In the last minutes, stars and planets will come apart, and atoms will be destroyed a fraction of a second before the end of time." Cool, eh?\n\nEarth's final resting place: HAH! If I knew that, I wouldn't need aftershave.\n\nFeasibility rating: 8/10. Likely. Assumes the Big Rip theory is correct, which it probably is, but might not be.\n\nEarliest feasible completion date: AD 20,000,000,000, assuming w = -3/2 (could vary)\n\nSource: a theory proposed by Robert R. Caldwell, Marc Kamionkowski, and Nevin N. Weinberg in February 2003. Read it here (PDF warning! Also, dense, difficult physics!). Brought to my attention by Jonah Safar and nanite.\n\nDecayed\nYou will need: all-surpassing patience\n\nMethod: If the Big Crunch doesn't happen, and the Big Rip doesn't happen either, then we come back to the third option: the Big Chill. For this, the universe will just expand, forever. The laws of thermodynamics take over. Every galaxy becomes isolated from its neighbours. All the stars burn out. Everything gets colder until it's all the same temperature. And after that, nothing ever changes in the universe. For eternity.\n\nA lot can happen in an eternity. Protons, for example, while incredibly stable, are believed to eventually decay like any other particle. So simply wait for a period of time of the order of 1,000,000,000,000,000,000,000,000,000,000,000,000 years, and roughly half of the constituent particles of Earth will have decayed into positrons and pions. If that's still too much like a planet for you, you could wait for another 1036 years, leaving only a quarter of the original Earth. Or wait even longer. Eventually there will be as little of Earth left as you wish.\n\nEarth's final resting place: Miscellaneous positrons and gamma radiation (pions decay almost instantly into gamma ray photons) scattered thinly across the entire universe.\n\nComments: It's interesting to compare this method with the one right at the top (total existence failure). What we are essentially doing here is almost exactly the same thing, only instead of expecting every particle to disappear at once, we are waiting patiently for a significant proportion of them to disappear, one at a time, over the course of an unimaginable period of time. Essenti
240810
Earth is 12,742 kilometers (7,900 miles) in diameter. That's how far you would have to tunnel to dig to the other side of the Earth!\n\nThe circumference of the earth at the equator is 24,901.55 miles (40,075.16 kilometers).
66810
Earth ranges from 7,926 miles to 7900 miles, depending on your location.\n\nThis is approximately 12,756km
280906
Supposedly the universe is estimated to be about 13.6 billion years old.  I think I read that on Wikipedia, though, so you never know...\n\nThat said, I really have so little idea what is out there or what conditions are necessary for life to arise that I don't know which theory is more plausible.  How flexible are the conditions that lead to the formation of primative cells on Earth?  Can there be life based on an entirely different set of molecules?  An entirely different set of elements (i.e. not carbon based)?  How many other planets have chemical compositions and climates like Earth?  Did life even originate on Earth? (I've heard the theory that primative cells could have originated on another planet and been brought here on an asteroid).  Could primative cells have left Earth on some sort of asteroid and taken up residence elsewhere?\n\nI'd like to think there's other life out there, just because it makes things more interesting.  Until I have reason to believe otherwise, I'll assume there is.
309054
given the figures, another way to "imagine" how far it is\n IS that Light (at 186,000miles/sec)takes about 8.3 minutes to get to earth from the sun and takes 5.5 hours to get to pluto\n\nPluto is 40 times the distance away from the sun as the earth \n\nOver 11,000 earths will fit between the sun and earth if lined up so about 460,000 earths fit between the sun and pluto.\n\nAlso if the Sun was a beach ball, the earth would be a pea and Pluto would be A LARGE grain of sand.\n\n\n\nThe numbers are often useless unless we "translate them" into "concrete" terms because we have peas er I mean grains of sand for brains ;)))).
247560
It depend if you are a religions person or believe in facts. Me, as a geologist I believe in facts and science.\nThe earth forms 4.6 billions years ago. How did we know? By using the radioactive decay method. \nNobody really knows how it form but you can get differrent references. Try historical geology books. \nEarth solidifies around 3 billion years ago, how? From the dated rocks namely Banded Iron Deposits. Life began at PreCambrain era. Meaning 512 millions years ago. Dinosaurs came to life at least 100 million years ago and died 65 miilion years ago because of  a comet hitting the earth.\nActually there are a lot more happend but for your satisfaction try to look for a Historical geology book. A very interesting book.
850619
This question is gibberish.  The circumference of the earth is about 25,000 miles.  I guess Chris W is the only one who can understand you and he doesn't know the difference between "our" and "are".  This site seems to be infested with ignorance.
61902
Earth is thought to be between 4.5 and 4.8 billion years old. The age of Earth is found by measuring the age of very old Earth rocks. This is done by measuring the rate at which elements of the radioactive metal uranium decay (break down) into lead. Scientists have also measured the age of meteorites which have fallen onto Earth's surface, and the age of moon rocks brought back by the Apollo astronauts. Both the meteorites and the moon formed around the same time as Earth, and they show similar ages.\n\nIf you want a break down of that timespan in terms of Geologic Periods, see:\nhttp://www.cotf.edu/ete/modules/msese/earthsysflr/geotime.html
978266
depends on a number of factors, how hot its burning, ours should be around for a few more billion yrs.
44586
The earth is not a perfect sphere. It's slightly 'wider' than it is tall, so you could measure the circumference at the equator (24,901.55 miles or 40,075.16 kilometers). If you go through the south and north poles (24,859.82 miles or 40,008 km)
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.
527612
Between 12 and 14 billion years.\n\nLearn more here:\n\nhttp://map.gsfc.nasa.gov/m_uni/uni_101age.html
675720
The currently accepted estimate is 4.5 to 4.6 billion years old.  Radiometric dating of Earth rocks can't get us there because the surface of the Earth has undergone so much upheaval.\n \nInstead, moon rocks and meteorites are used to estimate the age of the Earth, because it appears that all of the solar system formed at about the same time.\n\nCarbon dating is of no use here; it only works for organic material and it can't date back further than 50,000 years or so. Long-lived radioactive elements such as uranium are used instead.
369953
Read:http://pubs.usgs.gov/gip/geotime/age.html
604912
These astronomical questions require astronomical answers. How to start and how to end?\n\nFact is, our existence is only a very very very very.......... small portion of time to calculate. To find how old, we have yet to discover evidence mainly because we cannot reach outside our very own galaxy to explore. Considering that it will take lightyears to travel the enormosity of time and space boggles all that best is people to come with a reasonable reason that will be hard to disprove. No one can. All can theorise.\n\nSo the universe is so large, it is beyond our perception, beyond our present ability to fully comprehend, and though we are making small progresses with probes and telescopes, it is still too huge and complex to grasp. We can theorise based on understanding of our surrounding and equating everything else to what we know. This is our limitation. \n\nUniverse has been around even before our gaalxy is formed bbillion zillions years ago. The acceptable theory is that a big bang ceated our galaxy and out solar system. Something must happen, and people theorise it must be sudden, that is why the bang. And it just happen like that that our galaxy was formed, and then our solar system. No one can track back and so this is so. Hence, theory is what we can do to try to explain to ourselves.\n\nSupernova is a dying star, giving its last burst of energy befre collapsing. Death of stars is something little understood because it is rare. Stars take million of light years to reach us and so we are watching history when some event occurs. So far, only a few supernova had been documented. And these stars actually died millions years beforehand.\n\nIt is theorised that when a star dies, it collapse into itself, as stars are suppose to be like our sun, all gaseous. It is theorise that the star will collapse into a very dense body with very high gravitational pull that it sucks everything nearby into itself. This is the black hole.. It is theorise that it will be so dense that even light cannot escape. So far possible sighting of black hole has been done by noting the bending of light in the universe, since the black hole cannot be seen \n\nSo, outside our atmosphere, we have theories to try to explain everything we see. We need a reason to justify the things we see in space, rather than accepting that they are there even way before life begins on earth, and that there will be many flawed theories because at this time, it is just beyong our ability to check it out.