I will discuss results on the distribution of mass in galaxies as
measured by the motion of satellites using SDSS. Updated database of
SDSS and improved statistical methods allow us to measure
the three key properties of the satellites around galaxies:
the rms velocity, the shape of line-of-sight distribution, and the
angular distribution of the satellites. Using these results, I will put strict constraints
the LCDM model and on MOND. The LCDM fits the data remarkably well. This
extends the success of the standard model from magaparsecs down to 50kpc.
MOND has a unique prediction on those scales, which I will describe in
my talk.