I have read a lot of posted that claim that Comet NEAT was in fact Planet X, and that it was about the size of Jupiter.
This sprung from some fanciful imaginations since it was reported that the visible COMA (the tail ejecta) was in fact around 300K miles in diameter.
Howerver, this visible Coma is comprised of extremely dilute gas and dust, ejected as the icy core nears the sun, which heats it and boils off
volatiles from the surface of the core.
The average core of a comet is generally anywhere from 10 to 150 miles in diameter. Considering the massive Coma given off by NEAT, I would assume it
to be towards the larger end of this spectrum, but I still imagine it to be less than 100 miles in diameter at the most.
Even at this size of 100 miles diameter, NEAT is just a huge rock (OK, the size of a mountain range, but still just a big rock) in terms of
gravitational influence. Likewise, even if the entire solid core was of highly magnetic material, it is NOT going to severly influence the earths
(Not to say that the magnetic field of the earth is not doing something strange, and it may well be linked to the solar magnetosphere, but I doubt
that NEAT has much to do with it due to its small size. It is however very possible that NEAT may be interacting with the solar magnetosphere, as
there is evidence of attraction of large CMEs)
The main, and truly only, danger that NEAT poses to the earth is that of collision. I have posted extensively of the consequences if something that
big were to hit earth (not very pretty picture).
The chances of it hitting? To be honest, I dont like them. NASA has made asses of themselves on the subject, and to me at least, that is far more
telling than anything I have seen on the web.
We will just have to wait and see. If it happens, it will be around May 5-12.