S U N D A Y S O U R D O U G H

Hello! We've tumbled down the rabbit hole of autumn over here. Everyone else seems to be giddily unpacking sweaters and coats and posting pictures of mugs of tea next to their perfectly mussed pile of blankies, but I'm over here sulking. Fall is scary! It gets dark super early, my walk to the gym in the morning is pitch black and cold, and it's only going to get worse for the next few months. There is nothing to look forward to. Everything is bleak.

JK JK, not everything is terrible. My afternoon breaks from lab work look like this, now:



...and more importantly, turning on the oven no longer heats our apartment into a 600sqft sauna. Also, I like apples, so the loss of tomatoes + stone fruit from the farmers market is a little less devastating than it otherwise could be. Also, there's surf, because it's hurricane season.

Each fall, my non-scientist friends tend to ask me some variation on these two questions: 1) why do we have seasons, and b) why do the leaves change color? These are totally excellent questions that show that my friends, who are obviously great, are behaving like good little scientists: observing change in their natural surroundings and trying to figure out what mechanisms drive those changes. Nice!



Above, we see a rendering of the earth, with a US-centric orthographic projection (we can talk about map projections and shape distortion another time. Maps are super fun, and the earth looks really different from different perspectives). This projection is pretty common; we often see the earth represented as this sort of round ball oriented, vertically oriented, with the North Pole up at the top of the picture and Antarctica puddling at the bottom.

Of course, we could also look at the globe like this,

or like this (my view most of the time these days, since my research focuses on Antarctica and the Southern Hemisphere):


but for now, let's look at it in more or less the same orientation as that first few. It's still more or less vertical, but tilted a little bit onto its side. It's cocking its head at us, asking why we're staring at it.

The earth orbits around the sun every year. The angle at which the earth is tilted--how far over its head is cocked--stays the same for the whole time. I often find it helpful to physically move around to help myself understand how the orientation between sun and earth changes, so play along, if you'd like.

 Stand up and tilt your head to your left about 20 degrees (or about as far as any semi-flexible person can go without stretching too hard). Your head represents the earth; the northern hemisphere is basically everything north of your ears, and Antarctica is down at your chin. Pick a point a bit to your left to represent the sun, and walk in a counterclockwise circle around that point, facing the same direction the whole time.

When you first start, your northern hemisphere (your upper head, basically) is closer to the "sun" than your chin. That part of your head would get more sunlight than the lower half, and more sunlight in = warmer. In other words, it's summer up around your temple, and winter down at your chin. Keep Once you get halfway around your circle, your right lower-head-chin area will be closer to your sun than the top half: it's summertime down under!

We can make this the best new dance move, guys. Tilt and orbit. Tilt and orbit. The "tilt" puts one hemisphere closer to the sun than the other at some given point in time; the "orbit" controls which hemisphere is in that sun-facing position.  The end result is seasons, felt more intensely in the places that experience the largest

We'll talk about why leaves change colors next time, and I'll pair the explanation with a very fall-friendly sweet potato + chicken pot pie recipe in a whole-wheat sourdough crust. For now, let me tell you about these sourdough waffles we made last weekend.

My sourdough starters are happy and active; they really perked up after I started feeding them Bob's Red Mill dark rye flour, but that was getting expensive, so I transitioned them back to a 50/50 white:white whole wheat flour mix. The rye feeds had greatly increased the starter's activity, though, and the colony wasn't exhausting itself in the 12 hours between morning and evening feeds. When we got home on Friday evening at ~9pm, the little starter dudes were going strong, still totally puffed up, smelling like very ripe apples, and crying for a pat on the head. "OK, little guy," I thought, "if you're that excited, I've got a job for you." I scooped out about half a cup of the active starter and mixed it into a slightly-modified waffle recipe, covered it with a towel, and left it on the counter overnight.

The next morning, the batter had roughly doubled in size and smelled like wheaty apple cider. The waffles that came out were lighter and fluffier than any I'd had before, and I'm used to pillowy overnight yeasted waffles, which do not slouch when it comes to texture. The sourdough leavening was powerful enough to lighten up a 100% wheat flour batter, which, under normal baking circumstances, would have ended up as a dense little waffle bomb. Not so, here!


Overnight Sourdough Waffles, adapted just a bit from The Perfect Loaf:

• 2 cups milk (you can curdle it into buttermilk with ~1tbsp white vinegar to make the crumb a bit more tender, Just mix the vinegar into the milk and let it sit for ~5 minutes)
• 1/2 stick (4 tbsp) melted butter
• 1/2 c sourdough starter
• 1 tbsp sugar
• 2 c flour. I used all whole wheat this time, but a better proportion is generally 1 1/2c white: 1/2c whole wheat.
• 2 eggs (room temperature, if possible)
• 1/2 tsp baking soda (for that little bit of extra lift)
• 1/2tsp salt