Earth's recoil speed when jumping straight up

[ballahboy]

i have no clue how to do this problem...

How fast can you set the Earth moving? In particular, when you jump straight up as high as you can, you give the Earth a maximum recoil speed of what order of magnitude? Visualize the Earth as a perfectly solid object. In your solution state the physical quantities you take as data and the values you measure or estimate for them.

Can anyone help me with this?
btw, the answer should be about 10^-23m/s

 

[arildno]

Remember that your common center of mass remains at rest at all times..

 

[HallsofIvy]

Your mass times velocity must equal the Earth's mass time velocity (but with opposite sign in order that the total remain 0.