A biography of possibly the first Canary astronomer will be presented, based on the discovery of a set of mysterious old exercise books in the library of the IAC

Telescopio de Juan Valderrama, actualmente en exposición en el Observatorio Atmosférico de Izaña. Crédito: Museo de la Ciencia y el Cosmos, de Museos de Tenerife.
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The astronomer Juan Valderrama y Aguilar was born and lived in Santa Cruz de Tenerife in the XIX century. He observed from Santa Cruz in that century, and his observations were known internationally. For years his work remained hidden until a woman left some exercise books in the library of the IAC, and an IAC researcher, José Antonio Bonet, discovered them some ten years later. After a study of his life history, now his biography has been published in the form of a book, co-edited by the Cabildo of Tenerife and the IAC. The presentation of this work, titled Juan Valderrama y Aguilar, pioneer of Canary Astronomy (1869-1812, (in the original Spanish: Juan Valderrama y Aguilar, pionero de la astronomía canaria (1869-1912), will take place on Wednesday 26th September in the Museum of Science and the Cosmos, of Museums of Tenerife. The presentation will be attended by the President of Museums of Tenerife, Amaya Conde, the astrophysicist of the IAC Ignacio Trujillo, the authors of the book, Manuel Vázquez Abeledo and Jorge Sánchez Almeida, and the author of the prologue Sebastián Delgado Campos, of the study circle Amigos del 25 de Julio.

“We are surprised by the quality and the meticulosity of the drawings which illustrate the exercise books, the fact that the data obtained by Valderrama appear in the data bases used by modern astronomer, and above all that nobody had Heard of him. Is it possible that in Santa Cruz de Tenerife there was an astronomer of which the official history of the city has no record at all?“ we asked the authors of the book.

The answer to the last question is “yes”. Valderrama was completely unknown, but his scientific biography is fully worth recognition. Outside university and official scientific circles this man from Tenerife was well connected with the world of modern astronomy in his day. He wrote what can be considered the first article on astronomy published by someone from the Canaries in an international journal (Valderrama, 1886, L’Astronomie, Vol. 5, p. 388), and he wrote it when only 17 years old. Manuel Vázquez Abeledo and Jorge Sánchez Almeida, who performed the research on the manuscripts, have used the exercise books to construct a short biography which does justice to Valderrama as an astronomer.

Valderrama’s profession was as a civil servant in the Provincial Deputation, the organism which preceded the present-day island Cabildos. Between 1903 and 1912 he was the Director of the Municipal Meteorological Observatory of Santa Cruz de Tenerife, which made him responsible for supplying the meteorological information which appeared in the daily press of the epoch. He also wrote about astronomical phenomena such as eclipses and comets.

Among his most relevant observations is the discovery of one of the first known solar flares (sudden brightenings of sunspots which appear and disappear in minutes). He also observed a transitory lunar phenomenon which is still cited today, occurring in a crater called the “Circle of Plato” not far from the “Peak of Teide” on the Moon. 

The observatories where he gathered his data were, in the first place, facing the church of El Pilar, and later, when he was named Director of the Municipal Meteorological Observatory, on the roof of the present Town Hall of Santa Cruz de Tenerife. His telescope still exists, and is found exhibited in the Atmospheric Observatory of Izaña.

The book is available for 10 euros at the Musem of Science and the Cosmos.


Talk at the IAC by Manuel Vázquez Abeledo and Jorge Sánchez Almeida:

Web of the mystery about the flare of white light: https://www.agenciasinc.es/Noticias/Una-llamarada-solar-captada-desde-Espana-en-1886

Valderrama's notebooks. Originals: http://www.iac.es/servicios.php?op1=22

Juan Valderrama's interview (1908): https://jable.ulpgc.es/jable/el.progreso/1908/06/11/0001.htm?palabras=observatorio


  • Manuel Vázquez Abeledo (mvabeledo [at] gmail.com)
  • Jorge Sánchez Almeida (jos [at] iac.es)