This is the first known photo of a total solar eclipse
The first photo of a total solar eclipse was taken on July 28, 1851, by Johann Julius Friedrich Berkowski.
Total solar eclipses have been wowing humans since ancient times, but it wasn’t until the mid-19th century that we figured out how to photograph one.
In an era when we have images revealing galaxies billions of light-years away, a photo of the sun might not seem all that impressive. But for 1851, a photo of the total solar eclipse was a landmark.
Taken Johann Julius Friedrich Berkowski in the Prussian city of Königsberg (the modern day city of Kaliningrad, Russia), the image was commissioned by the Royal Prussian Observatory at Königsberg. Using the photo technology of the day, the daguerreotype process, the scene was directly exposed onto a polished copper plate, explains Hanneke Weitering for space.com:
Once it was polished to a shiny, mirror finish, the silver-plated copper was treated with halogen or iodine fumes that made it sensitive to light. Exposing the copper plate inside the camera would leave behind a latent image, or an invisible trace of the photograph.
To make a latent image visible, the daguerreotypist would treat the copper plate with mercury vapor in a dark room. Applying a liquid chemical treatment then removed the light sensitivity of the plate. Then, the daguerreotypist could rinse it off, dry it and seal it in a glass frame. The final product was a black-and-white image that was microscopically textured as a result of the silver's exposure to sunlight.
Others before Berkowski had tried, but the tricky exposure rendered earlier attempts over-or under-exposed, with issues of contrast a problem as well.
Berkowski’s photo, however, was just right. Using a small refracting telescope, the image required a 84-second exposure that he started as soon as the moon moved in front of the sun. The precision required must have been incredibly exacting.
While nowadays we can use our magical pocket-computer-cameras to take a photo of a celestial event and then transmit it around the globe in a matter of seconds, Berkowski’s eclipse daguerreotype stands as an iconic image of a medium in its infancy. I wonder if he took any selfies while he was at it.