Other factors and basic assumptions must also be considered.Of course, Kelvin formed his estimates of the age of the Sun without the knowledge of fusion as the true energy source of the Sun.
was published, the earth was "scientifically" determined to be 100 million years old. In 1947, science firmly established that the earth was 3.4 billion years old.
Finally in 1976, it was discovered that the earth is "really" 4.6 billion years old… The answer of 25 million years deduced by Kelvin was not received favorably by geologists.
Both the physical geologists and paleontologists could point to evidence that much more time was needed to produce what they saw in the stratigraphic and fossil records.
As one answer to his critics, Kelvin produced a completely independent estimate -- this time for the age of the Sun.
His result was in close agreement with his estimate of the age of the earth.
The solar estimate was based on the idea that the energy supply for the solar radioactive flux is gravitational contraction.These two independent and agreeing dating methods for of the age of two primary members of the solar system formed a strong case for the correctness of his answer within the scientific community.This just goes to show that just because independent estimates of age seem to agree with each other doesn't mean that they're correct - despite the fact that this particular argument is the very same one used to support the validity of radiometric dating today.He believed this even though he did admit that some heat might be generated by the tidal forces or by chemical action.However, on the whole, he thought that these sources were not adequate to account for anything more than a small faction of the heat lost by the Earth.Based on these assumptions he at first suggested an age of the Earth of between 100 Ma and 500 Ma.