5 If the Sun is losing mass at the rate of 5 million tons a second how can it possibly have lasted 5 billion years?

Answer 1

OK. We went to the web and collected a few figures. Now we'll work through the

numbers and see what we come up with for a ballpark estimated age for the sun.

The end result will be to flabbergast all of us at the vastness of the numbers, and

convince us again how unimaginable the numbers are.

Here's the data we got from the web:

-- Mass of the sun = 2 x 1030 kilograms

-- Fraction of the sun that is hydrogen = 3/4 (0.75, 75%).

-- Rate of consuming hydrogen = 620 million metric tons per second

Now we'll start massaging numbers:

Total mass = 2 x 1030 kg

Hydrogen mass = 0.75 of the total

Hydrogen mass already consumed = 0.25 of the total = 0.5 x 1030 kg

1 metric ton = 1,000 kg

Rate of consumption per second = 620 million metric tons = 620 x 109 kg

Number of seconds to have consumed the hydrogen that's gone, at the present rate:

(0.5 x 1030) / (620 x 109) = 8.065 x 1017seconds

Boiling that number down, it's equal to:

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9.334 x 1012 days

2.56 x 1010 years, or 25 billion years

This is far more than the figure we usually hear for the age of the sun. But it's only

some quick scratching on the back-of-the-napkin which ... to mention just one likely

inaccuracy ... assumes that the rate of consumption has never changed since the

first two hydrogen atoms fused.

In any case, it may be wrong by a factor of 1,000 in either direction, and it still

strongly suggests that the sun has been around for longer than any of us can

remember, and that it's not likely to flicker out at any time within our lifetime

or that of our 100-times-great grandchildren.

Even at 620 million metric tons per second.