Sunday, December 30, 2018

Now it is the New Year's Comet - Comet Wirtanen, Orbital Motion, and Diatomic Carbon Gas

Last night I got to try taking pictures of Comet Wirtanen again, with assistance from my son, who mostly wanted to run the "driver's seat" controls on the telescope mounting. When I processed the photos (stacking about a dozen) he noticed the comet was not uniformly green:

I asked my son (a kindergarten student) what he thought of the comet, and he said "two carbon atoms, they stickeded together, then got excited and glowed green, while on the bottom sunlight is just reflecting off the dust atmosphere [tail and coma]. Thank you for visiting my blog entry."

Put another way, the comet doesn't really show a tail in this photo, but the visible coma of the comet is not all made of the same stuff. Diatomic carbon molecules fluoresce green and are largely in the upper half of the comet's atmosphere in this photo.  In the bottom half, there is sunlight being reflected from dust particles (and in fact the nucleus itself) which is much whiter. This dust makes up one of the two tails a typical comet has, the dust tail that drags out behind the comet along the path of the orbit. The gas tail isn't really visible in this photo, but tends to point more or less directly away from the sun and is green in the case of Comet Wirtanen. For a better photo, look at SpaceWeather's comet photo gallery.

While the comet was approaching Earth, the tail seems to have been hiding behind the head of the comet, more or less. Now the geometry has changed rapidly as it sped past Earth, and the dust tail is coming out of hiding. This is a tiny comet that just came close enough to be a relatively easy thing to see - which leads to one of the reasons my stars are short lines instead of points - the comet is what I was tracking, and it is moving, even in the short span of time I needed to take these photos. is run by a public school teacher out of Bishop, California - the site maintains a collection of photos of interesting things in the sky submitted by folks around the world. This link goes to a movie of the comet moving among the background stars over roughly the same time I was taking my pictures. Comet Movie. This shows another object orbiting the sun moving against the starts as it moves away from Earth.

Tuesday, December 25, 2018

Christmas Comet - Comet Wirtanen

This was the 46th "periodic" comet discovered. In other words, it is in a stable orbit around the sun. This year it made a remarkably close - meaning several times the distance to the Moon - pass by the Earth. It is a little comet, yet even a little comet can be pretty and bright enough to see when it comes close.

This picture is a stack of 12 photos taken literally by putting my camera on its back on the ground and taking 12 exposures of 5 seconds each, then stacking them. No fancy gear needed, in other words. The comet is circled in the upper left, it is the faint fuzzy blob. Lots of folks have taken vastly better photos - this just happens to be mine. The Pleiades are in the lower center of the photo, and the Andromeda Galaxy in the upper right.

The neat thing about these sort of close-pass comets is that you can watch them move. Not quickly enough for the naked eye, but the comet had moved significantly between sunset and the time I took this picture, near eleven pm, at least it had moved its own diameter against the stars.

When planetary distances are considered, there are relatively few chances we have to watch things other than the moon move this fast.

Tuesday, December 11, 2018

Preparing Acorn Flour from Acorns

It's that time of year! We've collected a lot of acorns, mostly from the Tanbark Oak (Lithocarpus densiflorus), time to make flour!

If these were their close relatives, chestnuts, the process would be simple: shell, dry, grind. These acorns are full of tannins (the stuff that makes tea brown usually), so a few additional steps are involved.

Key things to keep in mind:

1. Dry the acorns as quickly as easily possible without heating them - we spread them in layers an inch or two deep on screens where there is good dry air circulation for a month or two. Acorns are susceptible to mold if stored moist for very long.

2. Do not heat acorns until you are completely finished with preparation of the edible flour and are preparing the final food item - heating these nuts or their flour early ruins the texture and prevents their "gluten-like" materials from showing their amazing properties.

Here are the steps we follow, in order:

Step 1 - Start with shelling the acorns. I have built power machines for doing this, which are messy and I am still unconvinced they saved any time, net. What I do these days for small batches is simply sit at the table while chatting, watching programs, or sitting by the fireplace, and simply shell them by hand using a basic nut cracker. There are several approaches, cracking at the cap end (the white oval is at this end) seems to work best for me, though others have good success putting the nut longwise into the nut cracker. Experiment and find what works for you. Discard any nuts that are moldy, darkened, contain bugs, or otherwise look "off". The shells and discarded nuts we use as mulch in the garden, they do compost given a bit of time.

Shelled acorns for Tanoak acorns look like this, note that not all acorns will have the papery husks.

Step 2 - Remove the husks. Not all acorns have these, so if you have exposed nut meats right after shelling, skip this part. This step is optional - it doesn't seem to be too much of a problem (or even frankly detectable) if the husks are ground with the nuts, I just do this because if the nuts are dry the husks generally fall off easily and it makes examination of the nuts to see if there are hidden bad spots much easier. If the nuts are dry, the husks are just going to fall off by rubbing handfulls of acorns between your hands. The chaff can then be blown off gently or the nuts picked out of the chaff. Discard any acorns with unusual coloration.

Step 3 - Grind the acorns. We put them in a kitchen blender and cover them with tap water until they are covered. Using a medium speed at first, and a high speed later, we grind the acorns into something with the consistency of a "smoothie".

Step 4 - Leach the acorns. We lay out a set of old towels on a screen (lots of ways to do this), with a relatively smooth and fine weave kitchen towel as the top layer. By using some rolling of the edges of the towels a raised rim can be made that helps keep the acorn paste in the center of the towel. Use a spatula to spread the paste out so it is fairly uniformly thick. This is the acorn cake you will leach. Acorn meal exposed to air will darken slightly, which is not a problem. Shown below is an improvised leaching stack on a plastic garden chair. Note - the towels will be permanently stained by this process.
While there are several ways of leaching acorns, this is our preferred one when we have cold weather and a suitable protected outside place to do the leaching. We put a Dramm Fogg-It seedling nozzle on the end of a hose and aim it from a distance at the cake, so that the mist falls evenly over the entire surface of the acorn cake and slowly flows through. We like this method because it can produce great results overnight, most other methods we have tried take several days in the refrigerator.
Every few hours taste the water dripping out of the bottom of the cloth. If it has no bitterness, the leaching may be done. Taste the wet acorn cake to be sure - it should not be bitter. When this stage is reached the leaching is complete and it is time to dry the acorn cake.

Step 5 - Dry the acorn cake. We allow the wet cake to drip for half an hour, then carefully fold the towel corners over the cake. We take this and compress it between layers of dry, clean, rag towels. You can put a cinder block atop the stack or other weight that doesn't care about getting moist. Let it dewater for an hour or so. If you can still squeeze water out by pinching some between your fingers, it needs another pressing with dry rag towels.

Once this initial dewatering is done, we place it on a warm, dry (not hot!) place and set up a slow fan near it. Leave it on the towel - it will continue to wick water out of the cake and help the drying. When the surface of the cake is dry, fold the towel ontop of it and crush the cake into lumps. The middle should be moist still. Allow the lumps (break into half inch or smaller clumps) to dry to the touch, then crumble them up and repeat until the crumbles are dry. Continue the drying for another few hours just to be certain.

Step 6 - Make "flour". In our case, we just put the dry acorn meal back into the blender and pulse it a few times to make a flour-like powder. This is now ready for use. Store in an airtight container in the freezer until ready to use.

Asking my son what he would like people to know about the process, he replied "when do we get to make acorn chocolate chip cookies?".

Up soon, Acorn Chocolate Chip Cookies!

Saturday, December 8, 2018

December Apples: Braeburn, Cripp's Pink, Yellow Newtown Pippin, and McIntosh

In early December the figs and finger limes are finished, the oranges and mandarinquats just starting,  and the apples are in their glory! We are down to four apples still on the trees - and these are the late gems. Yellow Newtown Pippin still hasn't reached it's prime, which usually happens after first frost.

From front right clockwise: McIntosh, Braeburn, Cripp's Pink, Yellow Newtown Pippin.

These are radically distinct apples. Getting them fresh off the tree is a profoundly different experience than getting unknown age apples off a typical store shelf. You certainly can get great apples at the store - I just don't know how to do it reliably. Going over them in that order:

McIntosh - this is our son's favorite. When I give him a choice of these four, he takes the McIntosh and tells me "you can have one of these [meaning any except the McIntosh he by now has bitten]". At this time of year these are tender (not mealy!) apples with amazing aromatics - these are richly fragrant, sweet apples, with deep flavor. This is the National Apple of Canada. For us, this is the fourth heaviest bearing apple tree in the yard. This month is the end of the harvest, they don't always last into December.

Braeburn - this is my favorite of the four. It is a firm apple with a sweet-tart apple flavor. This is the apple tree I planted outside the house back door (alongside Montmorency cherry), so I can have a snack without having to battle the autumn storms! It bears fairly heavily, our third heaviest and a very reliable one. These can hold on tree to the end of the month, generally, though gather them once frost falls.

Cripps Pink - this is in the market as "Pink Lady", though I prefer the older name. The apples are just now coming into their full flavor and sweetness - these are good. The tree bears heavily and the apples have been tasty since late August.

Yellow Newton Pippin - these are astounding! Unlike most US market apples, these have a light russett - the skin is rough in patches. These are firm, sweet-tart, flavorful, and the last apples on our trees generally - we've picked these at their prime still as late as  January (if we haven't eaten them all first...). This is our heaviest bearing and most reliably bearing tree.

Sunday, December 2, 2018

Golden Chanterelle Risotto

It's after a mushroom hunting expedition, cool Fall weather just begging for a warm, tasty, filling meal - showing off some of the Golden Chanterelles we found. Risotto is a tradition in our family, right along with Chicken Noodle Soup, despite having no known Italian in our heritage... with that note, this may not even be a proper "risotto", though we enjoy it! (and, in case you cannot tell, I do not depend on food photography for my livelihood...)


1 medium onion, chopped fine
1-2 cups of chopped or sliced Golden Chanterelles
2 tbsp. of olive oil
1.5 cups of Arborio rice
0.5 cup of white wine
5.5 cups of homemade chicken broth (or low sodium commercial broth)
0.5 tsp. of salt
0.5 tsp. of fresh ground black pepper
2 tbsp of fresh chopped celery hearts leaves
0.25 cup grated Parmesan cheese

Start with some Golden Chanterelles, enough when cleaned and diced to make about one to two cups of medium-diced mushrooms (we cut about 1/8" thick and perhaps 1/2" wide and 1" long at most - the thickness matters it seems, the rest is a matter of taste). Wash them (these are fine with being washed), trim off any bits that are imperfect, then dice.

Dice one medium yellow onion finely.

Add enough oil to a large pot to cover the bottom thinly (two tablespoons, more or less).

Add the onions and mushrooms. Apply heat and begin to brown the onions. When the onions are lightly carmelized, the mushrooms ought to be about right.

Add 1.5 cups of Arborio rice and stir to brown the rice, takes one to two minutes. The rice should be semi-transparent and the oil should be largely absorbed by the rice. Grains should be very lightly browned, at least in spots. There is a wide range of browning that is ok, though no need to overdo it - when in doubt, stop early.

Add 0.5 cup of white wine into the pot - there will be a lot of steam. Follow it by 1 cup of hot chicken broth (you need 5.5 cups of low-sodium or homemade broth) and start stirring, being careful to scrape the bottom of the pot often.

Every time the liquid level gets low, add more hot broth and keep stirring. It should take about half an hour on medium-high heat. This dish is an exercise program for your arms!

Once the rice is al-dente (you may not need all the broth, or may need a bit more - water is ok in a pinch), take it off the heat.

Stir in the chopped celery leaves, salt, Parmesan, and black pepper. Allow it to rest for a few minutes off the heat.

Stir once more and serve. Traditionally, more Parmesan is a good topping.


Saturday, December 1, 2018

Fall Mushroom Season in Full Swing

Cantharellus californicus - the Giant Golden California Chanterelle has made its usual appearance under oak trees within the coastal fog belt of Northern California. Today is the first day of December.

Yesterday, we found several under Coastal Live Oaks near sea level - Quercus agrifolia - though they appear under several species of oaks in our area. In our yard they appear under Canyon Live Oaks, Quercus chrysolepis. I am suspicious that they can grow on Tanbark Oaks, yet lack proof.

Please be aware there are poisonous mushrooms that can be mistaken for a Chanterelle, so don't start picking any edible mushrooms based on a book, a photo, or this blog. If you are interested, there is only one safe route to the practical knowledge - join a local mycological society and participate in some of the forays to become familiar with the local practices and rules. We are erratic members of the Mycological Society of San Francisco ( Good mycological societies can be found in many cities. While you might expect these societies to be full of scientists, generally there are many different constituencies - a large one of which often includes top local chefs!

This species is the largest chanterelle species in the world. Finding one is often enough for a quality risotto for the whole family (one of our normal ways of fixing them), though they can be sliced and sauteed or fixed any number of ways. Avoid freezing or drying this type of mushroom, the results can be disappointing.

There is joy in finding even just one of these. Asking my son about the one he found, he had this to say "but what about all the poison oak?" - he raises a good point, as Poison Oak often grows under these oaks (it is not an oak, but a low shrub or vine that causes horrible contact rashes, about a day after contact...).

If you do find one, there are tricks to finding more, however! First, stop moving. Stand still and look around - these rarely occur alone, more typically occurring in groups under the dripline of the tree. Second, these often do not push up far above the leaf litter - or at all - so look for low mounds with bits of chanterelle poking out at the edges. Here is what you often see when hunting these in the field:

Consider this our invitation to you to experience the joys of mycology and mushroom hunting!