Why isn't venus' dense atmosphere blown away by solar wind, even though it has no magnetic field?
Question:
Answer:
Slow rotation & gravity - oy - the pressure at the surface is 90 atmospheres or about the pressure at one km below the surface of any of our oceans.
It looks like the atmosphere can simulate a magnetic field:
http://www-spc.igpp.ucla.edu/personnel/r...
http://sunearth.gsfc.nasa.gov/sunearthda...
EDIT: Ignore my 1st answer, I changed it.
The reason is because Venus, at 3,760 miles around, is a much larger planet than Mars, at 2,110 miles so it has a higher gravity which holds on to its atmosphere.
Mostly it's held in place by Venus's gravity.
Doug
No specific explanation is available, however, the following extracts may shed light at your question and you may be able to figure it out by yourself why venus' dense atmosphere is not blown away by solar wind.
Extracts:
-Venus has no magnetic field, perhaps because of its slow rotation.
-There are strong (350 kph) winds at the cloud tops but winds at the surface are very slow, no more than a few kilometers per hour.
-There are no small craters on Venus because small meteors burn up in Venus's dense atmosphere before reaching the surface. Craters on Venus seem to come in bunches indicating that large meteors that do reach the surface usually break up in the atmosphere.
-Recent results from the Magellan gravity data indicate that Venus's lithosphere (crust and upper mantle) is stronger and thicker than had previously been assumed. Unlike Earth, convection in the defrming lower mantle produces stress on the surface which is relieved in many relatively small regions eposodically instead more continually at plate boundaries as is the case on Earth.
A magnetic field is not what maintains an atmosphere.
Venus has a weaker gravity than earth but it's atmosphere is much denser and heavier than earth's,solar winds nor anything else could blow it away.
If it's environment changed radically through chemical or other means I guess it could eventually become thin enough to lose it
I don't think that will happen for a while.
it's all about the gravity!!! vensus has a strong enough gravity to hold its atmosphere whereas mars is much smaller and therefore has a weaker gravity. secondly, the earths magnetic field isnt responsible for keeping our atmosphere intact, it just prtects us from harmful solar radiation. hope this helps!!!
Mars lost it's atmosphere due to interplanetary war not solar wind. The enemy bombed mars so severely that they destroyed much of the Martian crust. The heat and resulting forces blew the atmosphere off into space. In its last dieing gasp Mars managed to destroy it's enemy and thus created the asteroid belt out of their enemy's home planet. Then those still alive flew the Moon to Earth to start a new life. Us!
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