How old is the Earth?

Question

How old is the earth

Answer 1

approximately 4.567 billion years
http://en.wikipedia.org/wiki/Age_of_the_Earth

Answer 2

The 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.

Unfortunately, the age cannot be computed directly from material that is solely from the Earth. There is evidence that energy from the Earth's accumulation caused the surface to be molten. Further, the processes of erosion and crustal recycling have apparently destroyed all of the earliest surface.

The oldest rocks which have been found so far (on the Earth) date to about 3.8 to 3.9 billion years ago (by several radiometric dating methods). Some of these rocks are sedimentary, and include minerals which are themselves as old as 4.1 to 4.2 billion years. Rocks of this age are relatively rare, however rocks that are at least 3.5 billion years in age have been found on North America, Greenland, Australia, Africa, and Asia.

While these values do not compute an age for the Earth, they do establish a lower limit (the Earth must be at least as old as any formation on it). This lower limit is at least concordant with the independently derived figure of 4.55 billion years for the Earth's actual age.

Answer 3

The Earth formed around 4.57 billion years[1] ago and its only known natural satellite, the Moon, began orbiting it around 4.53 billion years ago. At present, the Earth orbits the Sun once for every roughly 366.26 times it rotates about its axis (which is equal to 365.26 solar days).[2] The Earth's axis of rotation is tilted 23.5°[3] (away from the perpendicular to its orbital plane), producing seasonal variations on the planet's surface.

Answer 4

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.

Unfortunately, the age cannot be computed directly from material that is solely from the Earth. There is evidence that energy from the Earth's accumulation caused the surface to be molten. Further, the processes of erosion and crustal recycling have apparently destroyed all of the earliest surface.

The oldest rocks which have been found so far (on the Earth) date to about 3.8 to 3.9 billion years ago (by several radiometric dating methods). Some of these rocks are sedimentary, and include minerals which are themselves as old as 4.1 to 4.2 billion years. Rocks of this age are relatively rare, however rocks that are at least 3.5 billion years in age have been found on North America, Greenland, Australia, Africa, and Asia.

While these values do not compute an age for the Earth, they do establish a lower limit (the Earth must be at least as old as any formation on it). This lower limit is at least concordant with the independently derived figure of 4.55 billion years for the Earth's actual age.

The most direct means for calculating the Earth's age is a Pb/Pb isochron age, derived from samples of the Earth and meteorites. This involves measurement of three isotopes of lead (Pb-206, Pb-207, and either Pb-208 or Pb-204). A plot is constructed of Pb-206/Pb-204 versus Pb-207/Pb-204.

If the solar system formed from a common pool of matter, which was uniformly distributed in terms of Pb isotope ratios, then the initial plots for all objects from that pool of matter would fall on a single point.

Over time, the amounts of Pb-206 and Pb-207 will change in some samples, as these isotopes are decay end-products of uranium decay (U-238 decays to Pb-206, and U-235 decays to Pb-207). This causes the data points to separate from each other. The higher the uranium-to-lead ratio of a rock, the more the Pb-206/Pb-204 and Pb-207/Pb-204 values will change with time.

If the source of the solar system was also uniformly distributed with respect to uranium isotope ratios, then the data points will always fall on a single line. And from the slope of the line we can compute the amount of time which has passed since the pool of matter became separated into individual objects. See the Isochron Dating FAQ or Faure (1986, chapter 18) for technical detail.

A young-Earther would object to all of the "assumptions" listed above. However, the test for these assumptions is the plot of the data itself. The actual underlying assumption is that, if those requirements have not been met, there is no reason for the data points to fall on a line.

The resulting plot has data points for each of five meteorites that contain varying levels of uranium, a single data point for all meteorites that do not, and one (solid circle) data point for modern terrestrial sediments. It looks like this:

Answer 5

About 4.5 billion years. at least for the second earth.

Answer 6

The Earth is older than the dinosaur
and as old as the stars.
Younger than the universe
and older than dirt.

Answer 7

As old as the universe, some 4.6 million years. This includes the period of its gaseous state too.
thnks

Answer 8

some would argue that the earth is only 6,000-10,000 years old.

Answer 9

approximately 4.6 billion years old.

Answer 10

about 4.5 billion years