In order to give members of the public an idea about the scale of the image they are looking at in JHV and HV.org, there should be an option to show some kind of reference measurement in the viewer window of JHV and HV.org. The reference measurement is a line of a fixed number of pixels length with a number and a unit next to it. The unit chosen refers to a well known object. The number changes depending on how zoomed in/out the view is, but the unit could change also depending on zoom. For example, when highly zoomed out the reference measurement could be a multiple of the size of the Earth i.e., 100 x Earth radius. On zooming in the reference measurement changes appropriately. At radii less than 1 Earth, the size scale could change to say, 'Atlantic Ocean', 'Europe', '10 x Rhode Island', etc. Metres or kilometers could also be given simultaneously, or via a toggle.
Submitting to JHelioviewer bug tracker so that request can be tracked separately for JHV and HV.org.