Photography, which has been around for nearly two centuries, is constantly reinventing itself. Who could have guessed 20 years ago that telephones would do double duty as cameras?
The first photograph was made in 1826 by French inventor Joseph NiÃ©pce. He used a pewter plate coated with a tarry substance that hardened when exposed to light and took a picture looking outside an upstairs window of his courtyard and out-buildings. The exposure lasted nearly an entire day – 8 hours!
NiÃ©pce then washed away the soft, unexposed tar, coated the hardened parts with ink and made an impression on paper to create a positive print of the scene. It wasn’t long before new, more efficient processes were developed, including the practical daguerreotype, invented in 1839 by another Frenchman, Louis Daguerre.
Here a thin coating of silver was applied to a copper plate and then exposed to iodine vapor, which converted the silver to silver iodide, a compound sensitive to light. A lens focused the image onto the plate, an exposure was made, and the photographer ‘developed’ the image with mercury fumes.
While the process may have been ruinous to your health, exposures were shorter andÂ images much sharper. The same year the daguerreotype was invented, John W. Draper, an American physician and chemist, used the process to take the very first successful photographs of a celestial object – the moon. Daguerre himself made a slightly earlier attempt but the picture was dark and not properly exposed.
Draper, at right, worked throughout the winter of 1839-1840 to get a clear lunar image using a telescope atop his rooftop observatory in New York. He finally succeeded with a 20 minute time exposure which produced an image only 1″ in diameter. The first pictures look crude to us today, but they clearly show the lunar seas (dark spots) and craters.
From there, astrophotography took off as astronomers quickly realized the camera could record a scene more faithfully and in greater detail than the eye. Longer time exposures and more sensitive film emulsions also meant a camera could see fainter stars, galaxies and nebulas entirely beyond the reach of the eye.
How quaint to think that prior to photography, astronomers sketched what they observed. The pencil was king! In the 20th and 21st centuries, professional astronomers almost never look through a telescope. Precious light from distant stars and galaxies is funneled through light-sensitive chips and stored on hard disks for later study.
Cameras have gone into space as well. Astronauts have packed them aboard orbiting spacecraft and all the way to the moon. Robotic spacecraft have carried the art of photography across the solar system.
As a demonstration of how far we’ve come since Draper’s time, I leave you with this amazing composite photo of the moon. It’s a mosaic of 1300 images taken over the course of two weeks last December by the Lunar Reconnaissance Orbiter (LRO). It looks a little different from the bright, flatly-lit full moon we’re accustomed to, because the orbiter took photos with the sun off to one side or the other in order to show lunar surface features with greater clarity.
For hours of free lunar fun, click on over to the full resolution image, where you can zoom and pan your heart away around the entire nearside of the moon. What a journey it’s been since that chill winter of 1839.