Why does this Nebula Have Two Lobes?

I am always fascinated by the diversity of colours, shapes, and scenarios that pop up throughout our universe.  Even though we can classify things into categories like ‘planetary nebula,’ ‘galaxy,’ ‘dwarf star,’ and such, there is still a huge amount of variability among these categories.  The most diverse group may be nebulae, since their shape relies on what elements are present, the environment in which they formed, and how far along they are in their evolution.  A great example of a strange and interesting nebula is the PN M2-9, the Twin Jet Nebula. Lying 5,560 light years away, in the...