Bonilla’s objects crossing the Sun

The surviving small photographic reproduction — José Bonilla (historical photograph); annotated reproduction via Wikimedia Commons
Processed image. A 233 × 204-pixel annotated reproduction attributed to Bonilla’s solar observation. The red arrow and labels are later markings, not features recorded in the sky. This is neither an original glass plate nor a newly recovered high-resolution exposure; enlargement cannot restore missing detail.
Public-domain historical photograph, published in the nineteenth century; Commons identifies the reproduction as public domain.
· Original image source · Image licence

José Bonilla reported hundreds of objects passing across his solar view at Zacatecas. Examine the surviving photographic reproduction and the assumptions behind explanations separated by more than a century.

World: Earth
Location: Mexico
Case date or period: 12–13 August 1883

A solar observer’s puzzle

The 2011 study by Durand-Manterola, Ramos-Lara and Cordero revisits Bonilla’s account of 12–13 August 1883. It describes 447 objects observed from Zacatecas and a report published in L’Astronomie in 1886. That is a count of reported objects, not 447 surviving photographs. The app offers one small photographic reproduction.

Read the photograph at its real scale

The available reproduction shows a bright solar disc and a small dark feature. Its arrow and labels direct attention but were added to the reproduction. Separate those markings from the photographic information. Heavy grain and the tiny source dimensions limit what can be inferred from the silhouette, even when the viewer makes it larger.

The nearby-object reading

Isaac Koi’s bibliography traces how the report travelled through UFO literature and earlier astronomical discussion. It records birds, insects and nearby material among the proposed explanations. The important question is distance: a small foreground object can cross a telescope’s solar view without being near the Sun. A striking silhouette does not settle that geometry.

A later comet hypothesis

The 2011 authors instead propose fragments of a comet. They interpret the lack of matching observations elsewhere as a parallax constraint and use assumed speeds to estimate distances. Their calculation is conditional: changing the speed or rejecting the geometric premise changes the result. It is a published hypothesis, not a confirmed comet identification or evidence of a spacecraft.

Keep observation and model apart

Make two notes: one describing what you can actually locate in the reproduction, another listing measurements needed to test an explanation. Independent timing, camera geometry and another observing station would be more informative than a sharper-looking enlargement. Koi’s source trail provides a route back through the debate; the later calculation should be read alongside its assumptions.