[meteorite-list] Dust, and millions and millions of years

From: Chris Peterson <clp_at_meteoritecentral.com>
Date: Tue, 26 Jan 2010 16:26:24 -0700
Message-ID: <5EC13200F03A46BD9A307BD29D4A1648_at_bellatrix>

It hasn't had much impact. Assuming that the Earth has accumulated 50,000
tons per year, every year for 4.5 billion years, the accumulated mass is
less than a billionth of the Earth's total mass.

BTW, I don't think we've lost much oxygen to outgassing. Oxygen is highly
reactive, and its concentration in the atmosphere depends on a combination
of biological and geological processes. It can be reduced (volumetrically,
not chemically!) in the atmosphere without being lost to space.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message -----
From: "E.P. Grondine" <epgrondine at yahoo.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Tuesday, January 26, 2010 3:59 PM
Subject: [meteorite-list] Dust, and millions and millions of years


> Hi all -
>
> "...approximately 40,000-60,000 t of extraterrestrial material
>>>> lands on Earth every year, the majority of which is in the form of tiny
>>>> dust grains usually less than 1 mm (1/25 in) in size; importantly, most
>>>> of this dust is believed to originate from comets..."
>
> So how massive was the Earth at formation, when the insects ruled, when
> the reptiles ruled, when the dinosaurs ruled? What percentage of current
> gravity during each period?
>
> We know that when insects ruled, the Earth's atmosphere had far more
> oxygen, apparently later out-gassed to space.
>
> I wonder what the long term future holds? Some quick math, Sterling,
> anyone?
>
> Ed "E.P."
Received on Tue 26 Jan 2010 06:26:24 PM PST