  We report here on the first proper motion measurements of molecular hydrogen
emission features in the Herbig-Haro 46/47 outflow. Assuming a distance of 350
pc to this flow, the inferred tangential velocities range from a few tens to
almost 500 km/s . The highest velocities are observed for H2 knots either in,
or close to, the jet/counterjet axes. Knots constituting the wings of the large
scale H2 bow (see, for example, Eisl\"offel et al. 1994) are found to move much
more slowly. These results appear to be in agreement with recent numerical
simulations of H2 emission from pulsed jets. We also report the first detection
of variability in H2 features for a young stellar object (YSO) outflow. It was
found that several H2 knots significantly changed their luminosity over the 4
year timebase used to conduct our study. This is in line with current estimates
for the cooling time of gas radiating shocked H2 emission in YSO environments.
