Reply #85: The effect should be trivial, I would think

[daleo]

I heard the approximate radius (maybe diameter?) of the object was about 400 meters, compared to the earth's radius of about 12,000,000 meters. So that is about 1:30,000 in linear measure, or about 1:27000X10e9 in mass, or in other words a mass differential of about 27 trillion times. Even a fairly close approach would have a negligible effect given that mass differential.

Note: these were just off the cuff calculations, and are approximations.

On edit - it is a close graze though, from the diagram.