This may seem like a newbie question, but I've been trying to answer this on my own and not making any progress. I understand the concept of the Constellation Plot intuitively as showing the membership in clusters as they're built up from the dendrogram. JMP puts labels on the axes (-200 to +200 in my case), which begs the question. The explanation that "Longer lines represent greater distances between clusters" doesn't really explain the two dimensions.