Expert: Tom Whiting - 10/27/2008

Question
Since the atmosphere of Venus is continuously being stripped by the solar winds, does any of it end up in Earth's atmosphere? Also, the constant stripping would mean that Venus is losing mass as well, is there a way to determine how much since its formation, and why the planet is so geologically active?

Answer
Hi James,
In reverse order, I would think that the planet is geologically
active in part due to the high surface temperature of 950 degrees
F, or hotter...and if so, I would also assume that lots of gases,
especially carbon dioxide and sulfides, are being continuously outgassing from the interior. I don't think we know enough yet
to determine whether Venus experiences continental drift and
techtonic plates like the Earth has....but it might.

I'm not sure we currently know how much solar wind stripping is going on; with over 90% of the thick Venusian atmosphere made of carbon dioxide (molecular weight 44) interspersed with sulfuric acid vapor and droplets H2SO4 -molecular weight 98) there may not be as much stripping as you think. Of course, this mass loss would be balanced in part by incoming meteors and space junk, just like on the Earth.
Remember, space is 3-dimensional, so escaping gases would form
a spherical 'shell' around the planet, so I think it's highly unlikely that there is any significant mass transfer from Venus to the Earth. (And come to think of it, most of those heavy gases
would be more apt to fall sunward, inward instead of outward, would they not?)  Mercury certainly hasn't 'sucked up' any Venusian gases as it has no measureable atmosphere at all. And it comes within 30
million miles of Venus about 3 times a year.
 
We only pass up Venus about once every year, and any gases stripped from the planet would highly disperse in the vacuum of space way before the Earth arrives at its minimum distance of 93-67 = 26 million miles of space between us, at inferior conjunction.
So I don't know of any way to determine, as yet, how much mass has
been lost since it's formation some 4.6 billion years ago, or
definitively why the planet is so geologically active, if it even
is. Other than radar images, we haven't done much work on the
surface of Venus due to the hellish conditions on the surface;
high temperatures enough to melt lead, and atmospheric pressure of some 90 atmospheres pressure, mostly carbon dioxide.
Clear Skies,
Tom Whiting
Erie, PA
PS...I don't think we even know how much mass loss the Earth has
suffered since formation, if any. Or even how to determine that
figure.

FOLLOW UP:
In addition I see no correlation between geologic activity and
atmospheres; the most active body in the Solar System is Jupiter's
moon Io, and it has a nil atmosphere. On the other hand, Saturn's
moon Titan at -250 degrees is probably very inactive, yet has an
atmosphere of nitrogen almost equivalent to Earth's nitrogen
quantity.  So, no correlation between geological activity and
atmospheres in my opinion.
Tom