Comet Tsuchinshan–ATLAS

Comet C/2023 A3 (cafuego. Wikimedia Commons)

 Comet C/2023 A3 Tsuchinshan-ATLAS has been visible in the evening for me for the past week or so. It's in the west for an hour or so after it gets dark. It's visible to the naked eye as a faint white streak, but much easier to see and and a more interesting sight with binoculars. The comet is getting less problematic to catch in some ways: it's further from the sun and higher in the sky, and the moon is rising later and waning, so the sky is darker for comet-viewing. But, the comet is definitely starting to fade and get smaller, at the same time. At it's best it was quite a nice comet, but still not nearly as bright and obvious as Hale-Bopp in 1997. 

Update: as of October 26, I can still find the comet with binoculars, but it's getting small and dim. I can't see it at all without binoculars, even knowing exactly where to look.

It's been a big month for astronomical happenings in New England, with the aurora borealis also making a rare appearance on a couple of nights. I caught them as kind of a diffuse pink glow in the sky. You can apparently see more structure with a camera with a good long-exposure astrophotograpy mode.

 

 

Eclipse Solargraph

Mansfield, Connecticut, looking to the south, April 8 to June 20, 2024.

 My solargraph of the 2024 eclipse, plus the next two and a half months through the summer solstice, turned out pretty well, but I'm not sure if I can really make out any eclipse dimming. Theoretically, the lowest sun track in the sky includes the April 8 partial eclipse, but it kind of blurs into the sunny days in subsequent, higher tracks. Plus, the sun is off the top of the picture in the early afternoon, when the eclipse probably was starting, because the camera wasn't pointed upwards enough. 

In the solargraph, permanent, stationary objects in the landscape, like trees, are visible in the lower part of the image, while the sun's paths in the sky over the course of the exposure are the arcs in the upper part. Sunny days show up as bright arcs, while cloudy periods (or eclipses?) leave dark bands. 

The solargraph was made in a soda-can camera obscura with a pinhole to project an image onto a sheet of black and white photographic paper. The actual physical photograph is an upside-down and backwards, pinkish-sepia negative image, burned into the emulsion on the paper. I used a flat bed scanner to digitize the negative, then inverted the colors and flipped the image to get the bluish positive image above. Solargraphic originals apparently can't be developed in the usual chemical way, because the emulsion has been exposed to enough light that it would just turn solid black. There are practical instructions online if you want to try solargraphy yourself. 

Scan of the original negative image.

Midsummer Conophytum Flowers

Conophytum pageae from southwestern Bushmanland. Nocturnal summer flowers photographed with a flash.

 Plants in the genus Conophytum are all primarily cool-season growers, and most species flower at the start of major vegetative activity in autumn. A few conos bloom at the summer solstice, though: Conophytum frutescens, C. francoiseae, C. minusculum ssp. aestiflorens, C. bolusiae, and certain forms of C. pageae are all flowering for me right now. 

Conophytum pageae has the widest geographic range of any Conophytum species, from the outskirts of the Knersvlakte in southern Namaqualand, all the way north into Namibia. There is a lot of variation in the plants over that range, and many species were separated out from C. pageae in the past. One of the more distinctive former species now considered C. pageae synonyms--Conophytum subrisum--is represented by the photo above. This particular batch of seedlings, from the southeastern part of the range of C. pageae, is a more or less classic "subrisum," with fairly large, greenish-yellow obconical leaves, with red lipstick-like markings late in the growing season, and flowers that are yellow, big and showy. Subrisum flowers also tend to happen very early, before the growing season otherwise starts and even in midsummer, as with these plants. 

There is a definitely an argument to be made in favor of maintaining C. subrisum as a separate species; the trouble is all of the variation and combinations of traits seen in wild populations of C. pageae in the broad, modern sense of Steve Hammer's revisions of the genus. So, there are southern plants that are C. subrisum in every way, except that they flower at the end of autumn, five months later than the population pictured here. Or, there are are plants with good subrisum flowers and leaf coloration, but with small, round plant bodies the size of peas. There are populations with plants that are vegetatively subrisum, but with puny pale-tan flowers reminiscent of the former Conophytum minutiflorum, another C. pageaae synonym. I really don't know what the best taxonomic solution would be in this case; in the balance between trying to name all of the variation seen in nature, and acknowledging that the boundaries between different forms are murky and shifting, maybe the best solution is to sink everything into one wide-ranging and problematically variable species, Conophytum pageae.

 

Graves' Beach Plum

Prunus maritima f. gravesii at the University of Connecticut, May 13, 2024

 

For this year's Endangered Species Day I thought I'd post about Graves' Beach Plum, which is about as endangered as a plant can get without being extinct, but which is also arguably not a species. Prunus gravesii was described in 1897, based upon what was likely a single plant with multiple stems, found growing near the shoreline in Groton, Connecticut. Later authors demoted the species to a variety, and then a form, of the widespread Beach Plum, Prunus maritima, and it is now usually referred to as Prunus maritima forma gravesii. 

Graves' Beach Plum native range was always minute, and the wild habitat of the shrubs apparently suffered during the 20th century from development, possible herbicide use, and the spread of invasive plants. By 1998, Graves' Beach Plum was apparently completely gone from its former habitat, extinct in the wild. Some internet sources have it that the little grove of Prunus m. f. gravesii was the only shelter near a beach without facilities, and the area was used as an open air restroom so much that all the plants died, but this seems to be a fairly recently invented legend. 

Prunus m. f. gravesii is extinct in the wild, not extinct extinct, because various botanical gardens and a few private individuals maintain the plant in cultivation. The New York Botanical Garden and the University of Connecticut Botanical Conservatory have kept it going for many years, and UConn has sent plants to the Arnold Arboretum and few other gardens.

Graves' Beach Plum foliage.

Graves' Beach Plum turns out to be charming ornamental shrub for sites in full sun, near the coast or otherwise. In mid-May it is completely covered by small white flowers, which attract large numbers of  bumblebees, mason bees, and other native pollinators. The plants can be propagated with some difficulty by stem cuttings, but more easily by dividing out the suckers that sometimes grow from the roots. Grave's Beach Plum differs from typical Prunus maritima most obviously in its smaller, more rounded leaves, but the entire plant is more delicate than the usual beach plum, with thinner twigs and smaller flowers and fruit. Fruit set in Prunus m. f. gravesii is never very abundant, and it apparently needs to outcross with other Prunus maritima to set seed, so seedlings are never pure gravesii.

Flowering shoots of typical Prunus maritima (top) and Prunus maritima f. gravesii (bottom).

 
Reference: Klooster, M.R. et al. 2018. Resolving the taxonomic identity of Prunus maritima var. gravesii (Rosaceae) through genotyping analyses using microsatellite loci. Rhodora 120: 187-201.
 

The 2024 Solar Eclipse

The April 8, 2024 solar eclipse in progress, through my projector. At least one sunspot is visible off center, and maybe some dust or bugs that got onto the screen. 

I didn't manage to get to northern New England to see totality in last month's solar eclipse, but I did catch about a 93% eclipse in Connecticut, which is enough that the light got pretty dim, shadows looked sharp with diffracted crescent sun images in them, and owls started hooting. It was neat, but nothing like the show when I caught the 2017 Great American Eclipse in South Carolina.

My jury-rigged binocular solar projector, this time with improvised tripod mount and screen.

Eclipse silhouette with button-hole crescent sun image.

Tree trunk shadows with crescent sun images.

Projection of the sun close to maximum coverage.

Solargraphy camera recording the action, with binocular projector in the background.

I set up a solargraphy (sometimes spelled "solarigraphy") camera to photograph the eclipse. Solargraphy is the process of using a camera obscura--usually a homemade pinhole camera made from soda cans--to capture photographs on black-and-white print paper, with very long exposure times, ideally resulting in a ghostly image of the landscape with the sun's track visible as streaks in the sky. I'll plan on stopping the exposure around the solstice in June, and will report back with the results then. Hopefully the first, lowest daily solar track in the photo will record a dimming as the eclipse progresses, but I already know that it won't include the sun brightening as the eclipse ended, because clouds moved in shortly after the peak of the partial eclipse at my location. [edited to add: finished solargraph here]