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Q: cosmology as geology ( Answered 5 out of 5 stars,   1 Comment )
Subject: cosmology as geology
Category: Science > Astronomy
Asked by: pelkeyrobyn-ga
List Price: $2.00
Posted: 17 Apr 2003 17:23 PDT
Expires: 17 May 2003 17:23 PDT
Question ID: 192044
how many tons of mass accrete to the planet Earth annually as a result
of meteors disintegrating in the atmosphere?
Subject: Re: cosmology as geology
Answered By: robertskelton-ga on 17 Apr 2003 20:38 PDT
Rated:5 out of 5 stars
Hi there,

Great question. I have investigated this previously, as possible
evidence for the "expanding earth" theory.

Any number a scientist conjures up can only be an estimate, and can
only be a current estimate - the Earth's past may have had a much
greater / much lesser interaction with meteorites than we have today.

Below we have figures of:

- 10,000 tons daily = 3.65 million tons per year
- 40,000 kg daily = 40 metric tons = 14,600 tons per year
- 50-100 tonnes per day = 18,250-36,500 tonnes per year
- 40,000 tonnes per year
- 78,000 tons per year

Consensus of opinion.... 40,000 tones per year

The Shreveport-Bossier (Louisiana) Astronomical Society, Inc. 
"On any dark night, an observer can expect to see half a dozen
meteors, but the total number that might be seen in any 24 hour period
from all points on the earth reaches an unbelievable figure of
approximately 90 million. "

"Tiny particles called micro-meteorites can also penetrate our
atmosphere without damage. These are falling continuously on us at an
estimated rate of 10,000 tons daily. This amounts to about 4 ozs. per
square mile per year."

Our Dynamic Earth
"Meteoroids and steroids are the debris of space, varying only in size
with asteroids being much bigger and varying in breadth from a few
metres to hundreds of kilometres. They are concentrated in an orbit
between Mars and Jupiter, often colliding violently with each other,
breaking down and eventually forming meteoroids which may be as small
as sand grains. Most meteoroids burn up when they enter the Earth's
atmosphere but some do strike the surface as meteorites. Meteorites
are important as their composition tells us something of the early
composition of the solar system. The number of meteorites which
survive the journey through the atmosphere, land on the Earth and are
large enough to be seen and found is about 2 per day. 40,000 kg of
material falls daily on Earth, most of it in the form of

ESA Directorate of Manned Spaceflight and Microgravity
"The study of micrometeorites collected in the Greenland and Antarctic
ice sheets shows that the Earth captures interplanetary dust as
micrometeorites at a rate of about 50-100 tonnes per day. About 99% of
this mass is carried by micrometeorites in the 50-500 µm size range.
This value is much higher than the most reliable estimate of the
meteorite flux, i.e. about 0.03 tonnes per day."
"Yet a great deal of space-dust falls unseen: each year, 40,000 tonnes
of asteroid and comet débris falls to Earth, most of it as tiny
particles called micrometeorites, less than 200 microns (thousandths
of a millimetre) across."

Dept. of Mineralogy (UK)
"Meteorites come in all sizes, from the very tiny - about one
thousandth of a millimetre across - to the very large; bigger than a
house. The smallest ones - micrometeorites - fall all the time:
approximately 40,000 tonnes fall on the Earth each year"

Museum of Natural History, Vienna
"The main mass of the daily infall (~ 100t/day, ~ 40 000 t/year) is
composed of pieces with a mass of approximately 10-5 g (or ~ 0.2 mm
"The daily influx of meteorites and meteor dust is well known to
scientists, but the total volume of mass daily added to Earth's
surface is difficult to estimate and is not well documented. 
Estimates of total volume published by NASA vary widely (or wildly?)
just for dust alone, ranging from as little as 1,000 tons/day (300,000
metric tons/yr, Dubin and McCracken, 1962) to 55,000 tons/day
(20,000,000 tons/yr, Fiocco and Colombo, 1964).  However, a more
recent estimate puts the accreting dust volume at approximately 78,000
tons/yr, or 214 tons/day."

Search strategy: micrometeorites tonnes

Best wishes,

Clarification of Answer by robertskelton-ga on 17 Apr 2003 20:45 PDT
But wait, there's more!

"However, I can still find a lot of different estimates for how much
stuff hits Earth each year, partly because different studies look at
different size ranges, and all the procedures have errors. Estimates
for the mass of material that falls on Earth each year range from
37,000-78,000 tons. Most of this mass would come from dust-sized

A study done in 1996 (looking at the number of meteorites found in
deserts over time) calculated that for objects in the 10 gram to 1
kilogram size range, 2900-7300 kilograms per year hit Earth. However,
unlike the number above this does not include the small dust
particles. They also estimate between 36 and 166 meteorites larger
than 10 grams fall to Earth per million square kilometers per year.
Over the whole surface area of Earth, that translates to 18,000 to
84,000 meteorites bigger than 10 grams per year. But most meteorites
are too small to actually fall all the way to the surface. (This study
was led by P. A. Bland and was published in Monthly Notices of the
Royal Astronomical Society.)"
pelkeyrobyn-ga rated this answer:5 out of 5 stars
Thanks for a very comprehensive answer. I'm trying to ascertain for
metaphysical purposes whether the earth can be considered a 'closed'

Subject: Re: cosmology as geology
From: neilzero-ga on 18 Apr 2003 04:33 PDT
Earth is approximately a closed system as far as mass is concerned but
cetainly not energy. We receive a large amount of energy from the sun
daily. An average of almost one KW (kilowatt) per square meter. Earth
radiates almost exactly the same amount of energy back into space
daily but on a longer wave length.
Even if we use the high figure of twenty million tons per year, that
is about 8 million cubic meters, when the dust and pieces get
compressed (they do eventually get compressed even if they take years
to reach the surface). Spread evenly over 450 million square KM of
Earth's surface = 450 trillion square meters, makes a 56 micrometer
thick layer annually. That is 56 meters per million years the Earth
grows in radius if I did not make an arithmetic error. The radius may
actually be shrinking if the average density of Earth is increasing
more than very slightly.
This is offset in small part by some hydrogen and much less helium
that is lost into space at the outer edge of Earth's atmosphere. This
amount is also unknown as much of this escaped gas stays close to
Earth's orbit and is swept up by Earth on subsequent orbits around the
sun. We do not know of any other loss of mass for Earth of
significance but there may be some.
 In the 2nd line of the table supplied by pelkeyrobyn 40 metric tones
is about 43 tons not 14,600 tons.   Neil

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