Earth Growth by Accretion of Meteorites?

Gerhard W. Bruhn, TU Darmstadt

Some authors think the Earth to be growing by accreting meteorites from space, see e.g. [3]. Each day the Earth is bombed by the huge amount of about 40 tons of meteor matter [4], i.e. 1.46·10¹⁰ grams / year. If we assume an average meteor matter density of 3 grams / cm³ (silicates), this yields the huge matter volume of about 5·10⁹ cm³ that Earth is growing each year. This volume is to be distributed over the whole globe.

But Earth’ surface is huge too, about 5.10·10⁸ km² = 5.10·10¹⁸ cm² . Hence we obtain a layer of 5·10⁹ cm³ / 5.10·10¹⁸ cm² < 10⁻⁹ cm that is distributed over the Earth each year, in other words, it would take 1 billion of years to sum up to a layer of 1 cm.

The author of [3] is convinced that the Earth circumference is growing by about 4 cm / year due to meteor accretion. For this purpose a layer of about 4 cm / 2π = 0.6 cm condensed meteor matter would be necessary, that would be a layer of about 1 cm meteor dust worldwide per year. Such an amount of meteor dust would be accumulated somewhere on Earth, in the Arctic ice, for instance, and we would know about such an effect. Thus we may conclude that there is no substantial meteor dust, and hence there is no substantial Earth growth due to meteor accretion.

References

[1] Alexander Braun u. Gabriele Marquart, Die bewegte Geschichte des Nordatlantiks, Spektrum der Wissenschaft 6/2001, p. 50 - 59.

[2] http://www.ngdc.noaa.gov/mgg/image/crustageposter.gif

[3] http://www.expanding-earth.org/

[4] http://www.astronomia.de/meteor.htm

[5] http://www2.mathematik.tu-darmstadt.de/~bruhn/EE-Berechnung.htm