The evidence for the continuing accretion of gas by the Milky Way involves high-velocity clouds, or HVCs--mysterious clumps of hydrogen, moving rapidly through the outer regions of the galaxy.
More than 40 gases are in the Milky Way.
( z1 gas :quant ( z2 more-than :op 40 ) :location ( z3 galaxy :name ( z4 name :op "Milky" :op "Way" ) ) )