From the second half of the 19th century, photographic images were recorded using glass plates. This device, covered by an emulsion containing silver salts sensitive to light, was used to record the daily lives of people, landscapes, nature and particularly the astronomical community, until the last decade of the last century, for the observation of celestial bodies. By having a low coefficient of thermal expansion, the glass plates ensure, over time, the accuracy and reliability of the astronomical measurements.
The photograph allowed a significant advance for astronomy and the development of astrophysics, recording the luminous intensity of the stars, as well as their spectral signature and their relative position in the sky. It allowed detailed study of nearby celestial bodies (planets, asteroids, and comets) and large structures, such as galaxies and clusters. In 1873 a systematic program of observation of the activity of the sunspots, eclipses and the solar corona.
This site shows the images of the photographic plates of the eclipse, realized in Brazil, municipality of Sobral - Ceará, happened on May 29, 1919, that contributed to prove the theory of General Relativity of Albert Einstein.
This collection of inestimable historical importance remains under the care and attention of the Observatório Nacional.
It is not our intention to make any comment or scientific analysis on the content presented.