Passage of Venus
About Passage of Venus
A short run of photographs shows a black disc against the sun, animated as Venus crossing the solar face. The frames come from a practice plate made for Pierre Jules César Janssen's photographic revolver, built for the transit of December 9, 1874. A 2005 study of the surviving plates concluded that the revolver plates still known are tests shot on a model. Plates exposed during the transit itself, if any remain, have not been located.
Cast & crew
More about Passage of Venus
Janssen tested the revolver in Nagasaki with support from the French government. Brazilian engineer Francisco Antônio de Almeida is named with him on the expedition. The camera used a Maltese-cross drive and was built to take 48 exposures in 72 seconds on a daguerreotype disc. The transit of December 9, 1874, ran from 01:49 to 06:26 UTC. The animation now circulated lasts about 6 seconds.
Themes
Background
The 1874 transit was the first of the nineteenth-century pair. The next was in 1882. Expeditions went out to time the contacts from widely separated stations.
Technique
Janssen's revolver tripped dozens of exposures at set intervals with a Maltese-cross mechanism, so the contacts of Venus could be timed from the plates.
Preservation
A 2005 study identified the surviving revolver plates as practice shots. The plates exposed during the transit have not been found.
Notes
- Janssen telegraphed that the transit had been observed at Nagasaki and at Kobe, with interior contacts on the revolver.
- The reel people watch is an animation of a test plate, not a continuous record of the transit.
- Daguerreotype was used because it could take the glare of the sun.
- The revolver's 48 frames were spaced across 72 seconds.
Scenes
- The disc of Venus sits on the bright face of the sun for a few frames.
Also available
- Internet Archive (1874PierreJulesCsarJanssenPassageDeVenus.webm.360p)
- Wikimedia Commons (1874 Pierre Jules César Janssen - Passage de Venus.webm)
