The observations of microlensing events in the Large Magellanic Cloud suggest that a sizable fraction ( \sim 50 % ) of the galactic halo is in the form of MACHOs ( Massive Astrophysical Compact Halo Objects ) with an average mass \sim 0.27 M _ { \odot } , assuming a standard spherical halo model .
We describe a scenario in which dark clusters of MACHOs and cold molecular clouds ( mainly of H _ { 2 } ) naturally form in the halo at galactocentric distances larger than 10-20 kpc .