Hello Bj”rn,

On Saturday April 27 2019 09:54, you wrote to nathanael culver:

 nc>> There's a a recent study or two which claim the earth is
 nc>> surrounded by a large hydrogen cloud (a geocrona) which extends
 nc>> out to about twice the radius of the moon's orbit.

 BF>    Space is not a perfect vacuum. It contains a few atoms per m^3.

In intergalactic space. Interplanetary space in Earth orbit vicinity is less
perfect. It nevertheless is a lot better than the vacuum in in the old vacuum
tubes. Open one up on the moon and the gas would /stream/ out.

 BF> That does not mean that they belong to Earth's atmosphere, defined by
 BF> the atoms and molecules that are retained by Earth's gravity.

"Gravity bound" is indeed a common definition used by astronomers.

Other definitions are in use as well, but by no definition generally accepted
by the science community, the moon is within earth's atmosphere.


Cheers, Michiel

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