The mass of the Sun is 316,000 times that of the Earth.
The mean distance of the sun is, say, 23,000 earth radii.
Hence the weight or pull of the sun by the earth is
316000 / (23000)² × 6 × 1021 tons weight.
In other words, it is approximately equal to the ordinary commercial weight of 36 × 1017 tons, as already calculated.
The Centripetal Force acting on the Earth.
Yet another method of calculating the sun's pull is to express it in terms of the centrifugal force of the earth; namely, its mass, multiplied by the square of its angular velocity, multiplied by the radius of its orbit;—that is to say,
F = M (2π / T)² r
where T is the length of a year.
The process of evaluating this is instructive, owing to the manipulation of units which it involves:—