I love a good coincidence. On Monday morning, I posted a gorgeous picture of the planetary nebula Abell 31, an object formed when a dying star blows off its outer layers in a series of winds which collide with each other. I mentioned that these nebulae are usually symmetric -- Abell 31 happens not to be because it's moving rapidly through space, and the gas through which it moves is compressing one side of it. But events like that are not the norm; most planetaries show stunning symetric features... like Henize 3-1333, as you can see in this nice Hubble image of it:
[Click to ennebulenate.] It looks like a flower, doesn't it? The petals you see are actually sculpted lobes of gas. I'm guessing it undergoes periodic episodes where it blows out gas in focused beams, which then move outward and form those features as they plow into gas ...
