Mark McCaughrean | But here’s the thing: because we have all of these older images of HH212 … we can see it moving ??
That is, because the material is moving outwards from the protostar we can see the jet expand over time.
It’s easily visible in this 22 year timelapse that combines three VLT images from 2000, 2007, 2018, & then the 2022 JWST image.
Measuring the changes, we can determine the expansion speed as 50-150km/s in different parts of the outflow.
