On the weekend I had two long conversations with Hans-Walter Rix about the Milky Way chemical abundance ratio gradients that I sent out to the APOGEE Collaboration this past week. Rix's view is that naive interpretation of poorly thought-out gradient estimates would set things in the field back; we should make plots of things that are (as much as possible) easy to predict, and we should interpret them with physically motivated models.
I agreed, and that led us down the path of working out the Right Thing To Do (tm). Of course this is to build a model of the star-formation history and inflow and outflow history of every molecular cloud in the Galaxy (and anything that has fallen into the Galaxy), and the IMF and all supernova and stellar-wind yields, and constrain this model with every star ever observed! So I did that on Sunday afternoon.
No, I didn't: I spent time thinking about what might be possible baby steps towards solving all of astronomy. Or, in other words: What would you do right now if you had 100,000 stars with 15 chemical abundances measured for each one? We have that!