astronomy

Morphology and evolution of the gnomon

The sententious fragment: In the tropics — that is, in the latitudes between the Tropic of Cancer and the Tropic of Capricorn — there are two moments in the course of the year when the sun passes directly overhead and an object won’t cast a shadow longer or wider than itself. The first of these occurs when the sun is on its way north to the Tropic of Cancer, which it will reach on the summer solstice; the second occurs when the sun is on its way back south to the Tropic of Capricorn, which it will reach on the winter solstice. For 2021, the first moment in tropical Honolulu was on May 26 at about 12:29.

The whole:

 

 

Restored, perhaps rightfully

The legacy of the Amherst College astronomer David Peck Todd (1855-1939) has been pity and derision. Astronomers know him as the but-for-the-grace-of-God colleague who almost but not quite discovered the moons of Mars and was defeated by cloud cover every single time he tried to observe a solar eclipse. Readers of poetry know him as the husband of Mabel Loomis Todd, Emily Dickinson’s first editor, who betrayed him with Dickinson’s brother. Julie Dobrow sums up the sad story at

http://www.juliedobrow.com/uncategorized/david-peck-todd-birthday/

In 1924, briefly released from the mental hospital where he spent his last years, David showed up in Washington and attempted to make radio contact with the Martians. I tell that sad story at

https://jonathanmorse.blog/2015/06/12/asks-air-silence-seeks-sign/

But he posed on the occasion in the observatory at Georgetown, and some photographs survive on the record in the Library of Congress. I observe one.

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“Dr. David Todd, Georgetown Observatory, 8/21/24.” National Photo Company Collection, Library of Congress, https://www.loc.gov/pictures/collection/npco/item/2016838239/.

Doesn’t the man in this image deserve to survive as he would have liked to be remembered — smiling and competent, at the controls in chiaroscuro and beautifully shined shoes? In hope for him and for us all, I photoshop.

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Some history on behalf of the Thirty Meter Telescope

Here, dating from 1854, is a view of downtown Honolulu.

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Here’s a detail from the lower right of the image.

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And here’s a double description of what your eyes have just beheld. One half of the description comes from the 1847 second edition of Herman Melville’s first book, Typee; the other half comes from an 1835 translation of what appears to have been Melville’s source, an 1834 account of an expedition around the world by the German botanist F. J. F. Meyen.

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And here are two more pages of Meyen which Melville didn’t use.

The_Foreign_Quarterly_Review.pdf

As I write, a group of Hawaiian monarchist protesters are holding up construction of the great Thirty Meter Telescope atop the Big Island’s Mauna Kea. They call themselves cultural practitioners, and what they claim to be practicing is the animist religion of pre-contact Hawaii. In this they are supported with money and public relations by Kamehameha Schools / Bishop Estate, the combined successor power of Hawaii’s nineteenth-century puppet kings and their Christian missionary puppeteers.

Typee is partially non-fiction, partially fiction. For a start, Melville’s “four months’ residence” in the Marquesas was only three weeks. As Hawaii’s history is generally taught, it too is partially fiction. But look at that illustration again. Look at that woman with her parasol and her Hawaiian slave.

It tells you that the things called history and culture are complicated, but sometimes they show us things that are true. So please: before you click away, look one more time at the man towing his missionary burden. He wasn’t a king or a priest. None of the people blocking progress on Mauna Kea today would claim descent from him. Still, he did exist, and perhaps he’s worth trying to remember.

Still image series: zenith passage, Honolulu, May 27, 2019

It happens only in the tropics — that is, the latitudes between the Tropic of Cancer and the Tropic of Capricorn. Twice a year there — first when the sun is on its way north to the Tropic of Cancer, which it will reach at the summer solstice, then when it is on its way  back south to the Tropic of Capricorn, which it will reach at the winter solstice — the sun at noon reaches a point directly overhead and a vertical object will cast no shadow. In Hawaii, where I live, the two dates will be in May and July. And the word tropic means turning point.

Today on Oahu, the still point (terms zenith passage or Lahaina noon) was predicted for 12:28, plus or minus a few minutes on different parts of the island. I set up my vertical object at 9:00 in brilliant sun and started shooting. The brilliant sun persisted until just about noon, but then the clouds rolled in. However, with the camera facing approximately north:

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Feel free to copy, but please credit me.

The arc of history

Only in the tropics — that is, only in the latitudes between the Tropic of Cancer and the Tropic of Capricorn — there are two days a year when the sun is directly overhead at noon and a vertical object, such as a flagpole, will cast no shadow. In Hawaii, where I live, one of those days occurs in May, when the sun is headed north to its summer solstice rendezvous with the Tropic of Cancer, and the other occurs in July, when the sun is headed back south to its winter solstice date with the Tropic of Capricorn. The astronomical term for the phenomenon is zenith passage.

Watch the shadow swing around its still point this year at

If you aren’t sure what you’re supposed to have seen, speed up the effect by sliding the cursor along the timeline and watching the shadow grow shorter and shorter on the west side of the foot of the stemware, then disappear, then reappear on the east side. The music is Bartók’s Music for Strings, Percussion and Celesta, movement 4, allegro molto. Seiji Ozawa, Berlin Philharmonic.

When the dark falls we can see a star

In 2015, at

http://theartpart.jonathanmorse.net/contribution-to-an-illustrated-edition-of-heidegger/

I posted a note about what then appeared to be the impending construction of a great astronomical telescope atop Hawaii’s 14,000-foot Mauna Kea. The construction was opposed with chants and picket lines by native Hawaiian shamans and University of Hawaii theoreticians interested in laying cultural groundwork for the dictatorship of the proletariat, but Barack Obama was President and I was optimistic. Optimistically, I illustrated my note with this fantasy of the telescope towering over the Black Forest ski hut where Martin Heidegger dressed up in peasant garb and went shrooming for the Authentic.

Heidegger's hut plus 30-meter telescope ATwo years later, it’s obvious that my Photoshopped optimism was incoherent. I had appropriated an architect’s rendering of the telescope in its rightful elemental night, but during the hours of his waking Martin Heidegger oversaw from the windows of his squat sturdy hut a mountain landscape brimming with illumined fog. Because I had left the night unmodified as a single layer of dark around the telescope, the image I manipulated couldn’t withstand the next two years. Image-fogging light overspread, innuendos of divinity took effect, and as of 2017 the sky has repopulated itself with horoscopic cartoons and there is a real possibility that the telescope never will be built.

But Photoshop offers everyone who sees an image the opportunity to resee it. Accepting the second chance, I will try to reimagine the telescope as if seen at sunset, when the shamans retire to watch Fox News. As dark flows up the flank of the mountain, the dome beginning its nightly labor of vision may serve thought as an emblem of hope: an eye opening to receive light from a not yet visible star.

Can anticipating sight and a star help us navigate a way of our own through the dark?

My noon had come to dine

Visible only in the tropics – that is, in the latitudes between the Tropic of Cancer and the Tropic of Capricorn – this is the zenith passage or Lahaina noon: the moment when the sun is directly overhead and an object standing vertically will cast no shadow. In the tropics it comes twice a year: when the sun is on its way north to the Tropic of Cancer (which it will reach at the summer solstice) and when it is on its way back south to the Tropic of Capricorn (which it will reach at the winter solstice). In Hawaii, where I took this picture today, the dates are in May and July.

And the picture’s title comes from a poem by Emily Dickinson, “I had been hungry all the years.”