Re: Age of sun and moon

Alan M Feuerbacher (alanf@mdhost.cse.tek.com)
Fri, 27 Sep 1996 10:13:51 PDT

Glenn Dixon said,

>I recently heard someone relating statistics regarding
>the age of the sun and moon that I would like to check
>up on. Specifically, what is the rate at which the
>intensity and or heat from the sun is diminishing?

I'd don't believe anyone knows anything about such long term
rates. Astronomers have recently found that the sun oscillates
in a great many modes and with many periods ranging from days
to hundreds of years. I don't think longer term data is
available.

>And what is the rate at which the distance between the
>earth and moon is growing?

About 5.6 centimeters per year at present. This corresponds to
a lengthening of the day by about 1.6 milliseconds per century.
Interestingly, correlation of the length of day with ancient
sediment layers indicates a non-linear increase over hundreds
of millions of years, so that a simple backward extrapolation
of present rates yields incorrect results. Ancient corals
about 400 million years old show that the year was about 400
days long then.

For more info, see Kent C. Condie, _Plate Tectonics & Crustal
Evolution_, Second Edition, pp. 19-20, Pergamon Press, Inc.,
New York, 1982 and _Scientific American_, October, 1982, p. 170.

Alan Feuerbacher