Fig. 1 - Three objects(!) with one in transit, March 1848
Solar Transits is a procedural exploration of the origins of astrophotography. Each image in this series depicts a randomly generated astronomical event but represented in the spirit of mid-to-late 19th century image capture techniques. The collection features a variety of rare alignments of stars, planets and moons, and are inspired by the aesthetic of daguerreotypes.
What exactly is a daguerreotype?
It is a remarkably detailed, photographic image on a highly polished, silver-plated sheet of copper, sensitized with iodine vapors, exposed in a large box camera, developed in mercury fumes, and stabilized with salt water or sodium thiosulfate.
The Artist’s Studio / Still Life with Plaster Casts
Louis-Jacques-Mandé Daguerre, 1837
The process is complicated by todays standards, but there are still a few people dedicated to preserving this technique. I reached out to Jerry Spagnoli, a renowned expert in the field. We collaborated on the creation of several physical daguerreotypes created directly from hand-curated images from this collection.
Photos of daguerreotypes are misleading. It is not obvious they are polished to a mirror finish. In order to clearly see the image etched into the surface, you have to angle the daguerreotype so that it reflects a dark surface. When it reflects a light surface, the image will appear in the negative.
The historical significance of the daguerreotype process cannot be understated. It allowed people to carry with them incredibly accurate depictions of loved ones. When the French painter Paul Delaroche saw a daguerreotype in 1840, he declared “from today, painting is dead.”
Within a decade of its invention, millions of daguerreotypes were produced around the world. However, by the 1860s, the art form had been replaced by newer and faster methods.
It is estimated that there are fewer than 100 photographers alive that work with the daguerreotype medium.
Total eclipse with prominant coronal flares
I am the speeding spark of light
flung by God
from the forge of Chaos
– Jónas Hallgrímsson
In June of 2012, I took a trip to Minneapolis to speak at the Eyeo Festival. Venus was going to transit while I was there. I was curious. I had not seen a transit before.
At 5:09 pm on June 5th, a nearly imperceptible black circle began its march across the sun. Were it not a predicted mathematical certainty, it is doubtful anyone would have noticed.
For six minutes, the light from the sun was 0.087% dimmer.
It is a significant thing to see an object silhouetted against the sun. We are so accustom to seeing our perfect circle of pure light that we can't help but to celebrate the occasions where something blocks the view. I still feel a little more special when a slight shadow shoots across the landscape on a cloudless day, the source being an extremely rare transit of a commercial jet liner.
Exponentially more rare is the planetary transit. When Venus hangs on the horizon, glowing against the night sky, it is all too easy to think it another star. Only when it is drawn as a silhouette can its position in our universe be fully appreciated: orbitally locked like us, and forever drawing it's path around the sun.
That tiny black circle effected me in a big way. The scale of the cosmos shifted into perspective. That doesn’t happen often. I was incredibly moved. It was an experience I will never forget. This project is an homage to that strange once-in-a-lifetime event.
Fig. 2 — Venus beginning transit
As it turns out, I was very lucky to have seen it at all. In the time since my birth in 1972, a Venus transit has only happened twice. The 1st time was in 2004 but I lived in a part of the world where it was not visible. The 2nd time was in 2012.
Unless I live to be 145 years old, there won’t be a 3rd time.
There are a couple silver linings: the Great American solar eclipse is on April 8 2024, and Mercury will transit in 2032.
Nearing occultation, red giant
A BRIEF HISTORY OF: ASTROPHOTOGRAPHY
The invention of photography is credited to Nicéphore Niépce. He captured the view outside his window using a camera obscura projected onto a pewter plate. The pewter plate was covered with a thin layer of naturally occurring asphalt which hardens when exposed to light. Because of how the buildings are lit in the photo, it is speculated that the process took at least 8 hours (some estimated it took multiple days). Niépce then washed off the unhardened asphalt and the resulting image was etched into the pewter plate.
From the Window at Le Gras, Nicéphore Niépce
Louis Daguerre discovered how to reduce the exposure time to less than 30 minutes. Daguerre is credited with taking the first photograph of the moon in 1839. Sadly his studio burned down two months later, destroying much of his experimental work including the historic image of the moon.
A year later, John William Draper took this daguerreotype of the moon, It is considered to be the oldest surviving record of astrophotography.
Moon, 1840, John William Draper
Five years after Draper’s daguerreotype of the moon, Louis Fizeau and Lion Foucault captured the first known photo of the sun. The five inch daguerreotype was clear enough to show sunspots on the surface.
Sun, 1845, Louis Fizeau & Lion Foucault
Johann Julius Friedrich Berkowski was the first to photograph a solar eclipse. In July 1951, he attached a small telescope to the Fraunhofer heliometer at the Royal Observatory in Prussia (now Kalinigrad in Russia) and captured an 84-second exposure shortly after the beginning of totality.
Solar Eclipse, 1851, Johann J. F. Berkowski
Warren de la Rue was the first to capture a photo of the elusive Baily's beads. Though they were witnessed many times before, the source proved elusive. It was through the photos of the 1860 total eclipse that the beads of light were determined to be the result of the sun’s light streaming through the irregularities of the moon’s edges, varied from complete roundness by mountains, valleys and craters.
Baily's beads/corona, 1860, Warren de la Rue
The first image below features one Sun, one Planet and one Moon.
The final output is comprised of 3 main layers: the background stars, the sun, and the silhouetted planets/moons. They were created using combinations of these five SDFs.
For most of these SDFs, red = x gradient, green = y gradient, blue = signed distance, and alpha was used for random extras.
Fig. 6 — Sun / Planet / Moon
Background stars SDF
Solar activity SDF
Noise LUT (4 LOD)
In keeping with the theme of photography, the code incorporates the notion of exposure time. The content is rendered at low brightness as if seen through a strong solar filter. The render frames are stacked for 3 to 5 seconds depending on the exposure settings for the final image.
Shorter exposures offer more detail on the Sun’s surface, whereas higher exposures bring out more detail in the corona.
Baily's Beads visible through clouds
The underlying composition generator
It became obvious early on that the corona effects would be the primary challenge. The planets and moons and background sky were straightforward to build, but the corona needed to express energy and drama. I decided to use a particle sim instead of trying to fake the field line aesthetic in a shader.
The coronal force field was created by scattering points with differing strengths and polarities along the edge of the sun disk. From these points I created a force SDF. The particles in the simulation would query this SDF in UV-space and apply the resulting data to the velocity.
The results from this method were fine, but very mathematically rigid and predicatable. The field needed more chaos and turbulence. I switched over to a GPU-based flocking algorithm and that provided enough potential for variety. Now, instead of following perfect arcs, the particles swarm through the empty space with organic intention while still being pushed around by the underlying force equations.
Two planets in alignment,
May 11, 1855