  We investigate how different models that have been proposed for solving the
dark matter problem can fit the velocity dispersion observed around elliptical
galaxies, on either a small scale (~ 20kpc) with stellar tracers, such as
planetary nebulae, or large scale (~ 200kpc) with satellite galaxies as
tracers. Predictions of Newtonian gravity, either containing pure baryonic
matter, or embedded in massive cold dark matter (CDM) haloes, are compared with
predictions of the modified gravity of MOND. The standard CDM model has
problems on a small scale, and the Newtonian pure baryonic model has
difficulties on a large scale, while a fit with MOND is possible on both
scales.
