dave boling
What is it?
The APoD is showing an unusual phenomenon going on in the Orion Nebula.
You know the constellation of Orion, right? The nebula is that bright spot near the end of Orion’s, ahem, belt. 
http://en.wikipedia.org/wiki/Orion_Nebula
Denny could explain this much better than I ever could. 
The small blue bubbles at the end of the conical yellowish things are small energetic gas clouds travelling very fast, the yellow cones are gas wakes/trails behind them. Well, small.. each of the small blue dots are ten times the size of our solar system.
-Tor