Originally posted by RJHinds
From the article the main figures we need to consider are:
1. Sun fusion rate - 620 million metric tons
2. Mass-energy conversion rate - 4.26 million metric tons
3. Age of the Sun - 5.57 billion years
4. Mass of sun today - 2×10^30 kilograms
To determine if the kid is right we need to calculate how big the Sun ...[text shortened]... .57 billion years ago? It is now 330,000 times bigger that the Earth, according to this article.
Using the Wiki numbers for now as they look at cursory glance to be accurate...
A trivial calculation for anyone with any ability to do maths whatsoever will show that if the
sun is converting mass to energy at a constant rate of 4.26E9 kg/s it will lose mass at a rate
2.556E11 kg per minute
1.534E13 kg per hour
3.681E14 kg per day
1.344E17 kg per year
1.344E20 kg per Ka
1.344E23 kg per Ma
1.344E26 kg per Ga
and 6.184E26 kg
over a 4.6 Ga lifetime to present.
Present mass appx 1.9891E30 kg
which means assuming a constant mass loss rate at present
levels means that the sun has lost a total of 0.031%
of it's present mass.
However even a basic knowledge of stellar mechanics would tell you that stars energy output
(and rate of mass loss) is not constant and in fact increases over a stars lifetime.
Thus the historic rates would have been lower and thus the total mass loss to date would also
be correspondingly lower.
EDIT: I should note however that the sun does have the additional mass loss mechanism of solar wind.
However the mass lost from this is an equally tiny proportion of the suns total mass.