OK, we all know Mars is further from the sun than Venus, we are told that Mars may have lost it's atmosphere due to it having no[or very little] magnetic field due to the effects of the solar wind. If this is all true and Venus also has a very weak Magnetic field [about 0.0015% of the earth's??] then why does Venus have an atmosphere olmost 100 times as dense as ours instead of it being blown away?. Any thoughts?