Expert: Jayendra Upadhye - 9/2/2009

Question
I have recently heard that the sun's Magnetic field was reversed back in 2008 with the sunspot cycle and all that. However my question is with the suns magnetic field being opposite to the planets wouldn't the planets be pulled in, slower affect on planets far away but faster on planets nearer?

thank you.

Answer
Hi,
Opposing poles attract!
There may be truth in that, but if I were to say "So what!! That has been happening for the past 4.5 billion years, every 11 years!!", then I too would not be wrong.
The reason:
1 - The earth though it is "small" compared to the sun, has stupendous amount of mass. Forget trying to imagine the masses of the gas giants, or the sun.
2 - The attraction due to "opposing poles" will be "Repulsion between like poles" in another 11 years! As the sun does not stay put, but its poles exchange positions cyclically every 11 years.
So it amounts to saying the sun pulls the earth and then repels it thanks to its magnetic field, essentially doing nothing if one averages out over the cycle.

The sum or gist of what I am saying here is that it is "Big deal!".

The mass of the sun is so large, that in those 11 years, hardly anything would happen.
Remember the sun's mighty gravitational field that holds the earth fast in its orbit?
Well its intensity in the vicinity of the earth (as per inverse square law is pretty low!
[A mere 0.006 meter /(sec squared)    G = 6.67*10^-19, M = 2*10^30, R = 148,800,000,000 meter and  Solar g near earth = GM/(R*R) ].

To quote from the wikipedia article on the sun,
[The interplanetary magnetic field is much stronger than the dipole component of the solar magnetic field. The Sun's 50–400 μT (in the photosphere) magnetic dipole field reduces with the cube of the distance to about 0.1 nT at the distance of the Earth. However, according to spacecraft observations the interplanetary field at the Earth's location is about 100 times greater at around 5 nanoTorr.].

refer:- http://en.wikipedia.org/wiki/Sun#Magnetic_field .

regards
Jayen