Monday, October 20, 2008

General: Have you ever used Google Answers?

Here is an example that I found fascinating!
(And you can see the search that I used to get this at the bottom)

Earth is getting a lot of space dust and meteors from space.
On the other hand our atmosphere is losing some gases.
Which one is greater? Is Earth gaining or losing?

Hello, and thanks for the question.

According to Jeff Brown at Washington State University,
several hundred tons of meteorites enter the Earth's
atmosphere every day. The total amount per year can range
from 10 million to 1 billion kilograms.
A lot of this is just dust or micrometeorites, but it adds up.

For example, let's say an average of 500 million kilograms
a year has landed on Earth over the past 10,000 years.
That's 5 trillion kilograms. Or 5 billion metric tons.
That might seem like a lot, but the total mass of the Earth
is over 5 x 1021 metric tons! (That's a 5 with 21 zeroes.)

The Earth also loses mass in several ways.
All the time, we're losing light elements, mostly hydrogen,
from the atmosphere.
In a study
( )
The author points out that
" present the Earth loses matter at a rate of 1 to 3
kilograms per second, the rate and composition varying with
solar cycle (sunspot cycle).
Recent measurements (K. Seki et al, Science 291:1939 2001)
suggest the rate is lower than this, but even with a net
loss of 3 kilograms per second, it would take 50 billion
years to deplete the Earth's atmosphere and at least another
15 trillion years to evacuate the oceans.
For comparison, the total lifetime of the Sun is only
approximately 10 billion years."

Assuming the worst case from this study, say we lose
That works out at: 3*60secs*60mins*24hours*365.25days or
94,672,800 Kg/year

So to answer your question, over long periods of time we gain
more from "space dust" and asteroids than we lose from the
escape of gases, but in some years it may be a net loss.

But gas escape is not the only way we lose mass.
Another way the Earth loses mass is through radioactive decay.
The Earth's interior is peppered with radioactive elements
such as uranium, thorium and potassium 40.
These radioactive elements are mixed in with other rock.
Granite, for example, can contain as much as four grams per
ton of uranium and 13 grams per ton of thorium.
As these radioactive elements decay, they give off heat and
in the process of releasing this energy, the elements also
lose mass.

Gary Collins, who is a physicist at WSU, says …
"it should be possible to figure out approximately how much
mass is lost, but it would be a difficult calculation"

Taken from: "Ask Dr Universe: The Big Questions" at
( )

And "space dust" and meteorites are not the only ways we
gain mass. For one, Earth gains a tiny amount of mass from
the "solar wind," the stream of charged particles from the
Sun's corona. This varies wildly, as you’ll find from the
NASA site on the solar wind here:
"The Solar Wind"
( )

Hope that answers your question,
but if you need clarification, just ask.


Google search used
earth mass gain loss

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