Net effects of Solar wind on Earth?

I checked the archives and made a cursory search on the 'Net and couldn’t find this information, so am throwing it open to the Teeming Millyuns:

a) has anyone calculated the net acceleration imparted to the Earth by solar wind? IOW, is the Earth’s orbit gradually increasing due to this effect, and if so, by how much?

b) Is the Earth’s atmosphere gradually being stripped away by the solar wind, or is the atmosphere being replenished, (by, say, infall of gases, water, whatever, due to gravity) at a rate greater than it is being eroded?

TIA,

In answer to A from Britannica Online ( http://www.britannica.com/bcom/eb/article/5/0,5716,70345+1+68567,00.html?query=solar%20wind )

For B I have a WAG:

The solar wind is mostly protons and electrons but there are some nuclei in there as well.

Now think of looking at the earth as a round disk (looked at head-on…not edge-on). The solar wind would strip atmosphere around the edges only as it blew by. The vast majority of the wind however would hit inside of the edges. If anything I’d say the mass of the earth is increasing. I’m not sure how adding mass to the earth would affect its orbit if at all. On the whole the the net effect must be very small if it exists at all. Four billion years and we still have an atmosphere so I’d guess all is ok on this count.

(Actually I’m not even certain the stripping at the edges would be so great since the earth’s magnetic field funnels some of the solar wind down towards the planet as well.)

Also WAGging, but what about the effects of drag? Not only is the solar wind blowing out against the Earth, but the Earth’s plowing through the solar wind on a tangent course, which will circularize and shrink the orbit. I’m guessing the timescales are on the order of hundreds of billions of years or more, though.

Well, the solar wind would have exactly zero effect on the Earth’s orbit. The net force on the Earth is slightly less than it would be if it were gravity alone that was acting, but it’s the net force that determines the orbit, and that’s the orbit we’re already in right now. As for effects on the atmosphere, the solar wind particles only actually reach the atmosphere near the poles, thanks to the effects of the Earth’s magnetic field (which is why the aurorae occur near the poles). I don’t think that there’s any net effect on the atmosphere, increasing or decreasing. It’d certainly be a smaller effect than the natural evaporation of the atmosphere into space.

Hmmm, mostly WAGs, and obviously not a burning issue.

Thanks to those who replied.

As you can see from this link…
http://itss.raytheon.com/cafe/qadir/q2722.html
The mass of the solar wind is very small. And considering that the wind goes in all directions, only a very small fraction of that small mass actually hits the Earth.

Here’s the density of particles hitting the Earth at the poles…
http://itss.raytheon.com/cafe/qadir/q2732.html

Here’s the mass increase on Earth…
http://itss.raytheon.com/cafe/qadir/q2723.html

The solar wind does affect the Earth’s magnetosphere…
http://itss.raytheon.com/cafe/qadir/q1213.html