I don't find the explanation about the Southern Cross very clear. The standard rule -as I know it- is: extend the "long" axis of the cross, in the "foot" direction, four and a half times. csiro.au/helix/sciencemail/activities/images/CruxLength.jpg Further, the rule "go towards the ground" is not reliable, sometimes the cross can point upwards sydneyobservatory.com.au/2010/…