  It has been argued in a number of recent papers that dark matter is in the
form of Jupiter mass primordial black holes which betray their presence by
microlensing quasars. This lensing accounts for a number of characteristic
properties of quasar light curves, in both single quasars and gravitationally
lensed multiple systems, which are not explained on the basis of intrinsic
variation. One prediction of this idea is that Jupiter mass bodies will be
detected by the MACHO experiment as short events of about 2 days duration,
although the expected frequency of detection is still very hard to estimate.
However, the recent report by the MACHO group of the detection of a Jupiter
mass body in the direction of the Galactic bulge is consistent with this
prediction, and is possibly the first direct detection of non-baryonic matter
in the Galaxy.
