We captured the Sun in a photograph for 10 months in a row and this is the incredible result


Modern mobile phones and digital cameras have sophisticated sensors and complex lens systems to capture any subject with the highest possible quality. During the last centuries, humanity has developed and improved photography techniques to capture a moment so that it can last over time. However, they have certain limitations that allow them to collect light for fractions of a second, unlike their original form, the camera obscura. Such is the case of the Solarcan, an instrument that allows you to capture continuously for hours, days, months or even years. At AstroAventura we installed one of them for ten months and six days in the first analog habitat in Colombia.

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Long exposure photography for ten months with Solarcan/AstroAventura.

The heavenly path: the trajectory of the zodiac

In everyday slang, midday is referred to as the time when the Sun is at its maximum point in the sky, also known as the zenith. However, reality is more complex, the star changes day by day the path it takes from its rising to its setting, in a cyclical period that repeats between the equinoxes. This phenomenon is produced by the inclination of the Earth's axis with respect to the plane of the orbit, and is in turn responsible for the seasons, such that its effects are more notable at greater distances from the equator.

Sunspots seen on February 10, 2024 from Bogotá. North is to the right. Credits: @fotografadany.

This is a phenomenon that on a small scale, in a matter of days or even weeks, can be imperceptible. But when you compare the direction in which the Sun rises or sets several months apart, the change can be distinguishedr. Places where the Sun did not enter before, such as a room partially covered by a building, are then illuminated at certain times.

Although there are now numerous tools or pages that generate a detailed report on the trajectory of the Sun, normally used for home design, there are analog alternatives to perform this same task and obtain striking results.

Solarcan: the simplest camera in the world

The Solarcan, the creation of Sam Cornwell, seeks to return analog photography in its simplest form to amateurs and professionals around the world. Allowing not only to record the Sun over days, months or years, but also to create an experience around the entire installation, capture, waiting, developing and editing of the image. It is also the perfect excuse to learn and discuss the changes in the Sun's path and the strong influence of the Earth's movement throughout its orbit.

Although there is a different model manufactured by the same person, the Solarcan PUCK, on this occasion the Solarcan. As its name in English says, it is a can similar to that of soft drinks intended for studying the Sun. This works like a camera obscura, through the effect pinhole, where a tiny hole of the order of half a millimeter is drilled that allows light to pass inside. Inside is a paper sensitive to this, such that it changes its color when exposed to an intense light source.

The special paper covers almost the entire interior wall of the can, the final image has a field of view of up to 160 degrees. Contrary to the Photography traditional analogue, where development required additional chemical processing, the material used for Solarcan and the chemical reaction produced by the intense sunlight causes a clear darkening. At the end, the result is extracted and scanned, to finally carry out post-processing and color adjustment.

Solarcan anatomy
Operation and structure of a Solarcan. Credits: Sam Cornwell.

The Solarcan, as well as her sister, the Solarcan PUCK, can be purchased on its official website. The first is valued at £19.95 and is shipped from the United Kingdom to all over the world. It can also be purchased in a pack of five or in different colors.

HAdEES-C: a Martian home on Earth

Once with the Solarcan In our hands was the difficult decision of the place and time to install it. Several proposals emerged, although some were limited by permits. The final option was Colombia Simulated Space Exploration Analog Habitat, from Cydonia Foundation.

This is a place whose objective is to bring the general public closer to space sciences in its different branches. As well as carrying out analog or simulation missions, where certain conditions are sought to be replicated.

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Photograph of the interior of HAdEES-C, the area corresponds to the place of work and exercise./AA

Near Bogotá, in Chía, the habitat is located. It was designed and built by numerous volunteers driven by the Colombian aerospace dream. It is inspired by similar facilities in the United States and Europe, with the focus of facilitating people from Colombia and Latin America to live the experience of an analogous mission. Where it seeks to simulate space travel, with key aspects such as isolation, limited food and water and the consequent effects on a psychological level and the development of the different objectives.

On March 11, 2023, before the equinox, Solarcan was installed. At the end of a day of repairs, maintenance and improvements to the habitat, several people from the Cydonia Foundation met with the writer to direct the camera, remove the security seal and begin collecting light for the next few months.

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HAdEES-C on the night of the Solarcan/AA installation
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The panorama towards which the Solarcan/AstroAventura was pointing.

Collection and development

The Solarcan allows you to obtain extreme exposure times, considerably longer than digital cameras. He pinhole or hole restricts sunlight to passing in a single straight line onto the paper. Due to the absence of lenses there are almost no deformations in the image, therefore, the marked path is shown with great quality. Likewise, the paper does not return to its initial state, permanently accumulating the intensity of the light received.

After ten months and six days of continuous observation, the seal was reinstalled and the Solarcan recovered. The next step was the extraction of the photographic paper, scanning and post-processing of the image. For this, a can opener is used in a partially dark room, in order to protect the sensitive material from sunlight and irreparable damage.

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The condition of the explanatory sign after more than ten months of continuous exposure to the outside/AA
Photograph of the habitat, the Solarcan and the rock garden at the end of the capture/AA

Once extracted it is possible to see the long-awaited photograph for the first time, in a sepia filter the first details can be seen. The dark lines show the path of the Sun, as well as its total or partial occultation by the passage of clouds, providing a considerable amount of information about the climate throughout the year. The wait is finally over, only one last step is necessary, improving the image.

light curves

Once the photograph has been scanned in the highest quality possible, you can use different editing programs such as Photoshop or GIMP to adjust certain aspects. In this case, Martin Morala was in charge of, with the help of Lightroom, invert the colors, really showing the sunlight and the contrast it makes with the rest of the environment. They also better highlight the details of the environment where it was installed, such as trees, mountains, buildings or similar.

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Long exposure photography for ten months with Solarcan/AstroAventura.

The Solarcan was installed in such a way that it pointed towards the west, the direction in which the Sun sets, and captured not only the sky, but also the mountains of Chía and the place where HAdEES-C is located.. The photograph, once with the colors inverted, reveals a structure similar to a square in the foreground. This is a box that is part of a project focused on replicating different reliefs and terrains on a small scale, where the aim is to test the performance and mobility of rovers. As well as carrying out a general analysis of the different processes that forged these forms.

The crossing of the Sun

The movement of the Sun in the sky is perfectly known and predictable. The installation date was not chosen at random, instead, it was carefully planned to show certain aspects.

In March the equinox takes place, at which time the star is in the west, with a slight deviation towards the south due to the time difference between March 20 and 11. The Sun moves north every day, until the June solstice, when it finds one of its maximum points. Afterwards, it retraces its steps until reaching the west again at the September equinox and continues to its other maximum point to the south during the December solstice.

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The analemma represents the movement of the Sun throughout the year. It is created from photos every few days at the same time.-NASA

About a month later, the Solarcan It is recovered and the capture stopped. Each line, dot or absence of both shows the weather at a certain time over a total of 312 days. It is necessary to mention that due to the ten months of photography and the two equinoxes, in certain cases a certain part of the photographic paper was exposed to the light beam two or three times. Which, if the weather permitted, represents a saturation or false reading of the weather on a given day.

Original SolarCan
Original scan of the Solarcan/AstroAventura.

A thousand stories on a sheet

HAdEES-C It was located on the left side of where the SolarcanHowever, due to the nature of the optical system, the direction is reversed, with north facing left. For this reason, on the right side of the photograph the outline of the airlock, a place designed to simulate pressurization and depressurization for extravehicular activities.

Since paper is only sensitive under intense sunlight, the rest of the objects and the environment do not show any major variation in tone, appearing as contours with slight differences.. A complementary photo is necessary to discern what each part of the photograph corresponds to.

The original expectations were high, but the reality was better than expected. Due to the geographical location of Colombia, being at a very low latitude and having part of the territory on the equator, the variation in the solar path does not move considerably away from the zenith. Unlike other examples of images captured by the Solarcan, in this case the aim was not to capture the complete arc, but to show the daily change of the direction over which it is hidden.

While the results are incredible, it was originally expected to capture some of the solar eclipse partial of October 14, however, on that day the sky was mostly covered by a dense layer of clouds, almost completely blocking the light.

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Definitive photograph of the Solarcan, color and contrast adjustments reveal a large amount of detail/AstroAventura.

Another aspect to highlight, when comparing with the panorama of the photograph taken after the installation, is the little detail of the mountains in the background. Where only a faint moving outline is shown. The same is evident in the height at which the lines of the Sun disappear. The shift between the left and right sides is presumed to have been due to a slight disturbance in the direction in which the sun was pointing. Solarcan.

Reflection under the Sun: learning

The Solarcan It is not just a camera, but it is a complete experience that allows you to delve into the nature of the Sun. It is a way to go beyond the everyday photograph of a sunny or cloudy day, or the beauty of a sunrise or sunset. It extends horizons by several orders of magnitude, creating a snapshot of changes over the course of a year and the changes that take place.

It is a tool to contrast the evolution of the climate, showing, for example, the low cloudiness in January 2024 in the form of almost completely continuous and dark lines in the right region of the photograph. And remember the importance of understanding and counteracting the effects of climate change, noting the effects that the El Niño phenomenon has shown throughout the Latin American region in recent weeks and on the global panorama over the years.

According to the creator of the Solarcan, this was the first sent to Colombia. And it is a clear example of its potential, opening the doors to several similar works, as well as extensions or modifications that allow students and in general all citizens to rediscover the wonders of the country.

Francisco Andrés Forero Daza
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