How Much Space Material is Needed to Alter Earth's Gravity?

[mapper]

Apparently we get tons and tons of material dumped yearly onto our planet from space. Just wondering how much would be necessary to affect Earth's gravity so we can see a measurable change and how long that could take? How would you go about figuring/calculating this? Would it be millions of years or longer?

So say a 50 kilometer object were to pound into the earth, although we would surely all perish would something like this effect Earth's gravity to the point of being measurable?

 

[dextercioby]

Let's say it "sticks" to the Earth,so that total mass is M_{initial,Earth}+M_{object}.Compute the mass of this object,as to produce a variation of "<g>" to let's say 6-th decimal.Assume mean radius to be the same b4 & after the impact.

Daniel.