The MACHO project detected the first instance of the gravitational lensing of one star by another , known as Gravitational microlensing , in 1993 ( Alcock et al. 1993 ; Paczynski 1996 ) .
The MACHO project found the first example of the gravitational lensing of one star by another , known as Gravitational microlensing , in 1993 ( Alcock et al. 1993 ; Paczynski 1996 ) .