Annibale Riccò (14 September 1844 – 23 September 1919) was an Italian

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

Biography

He was born in

Milan Milan ( , , ; ) is a city in northern Italy, regional capital of Lombardy, the largest city in Italy by urban area and the List of cities in Italy, second-most-populous city proper in Italy after Rome. The city proper has a population of nea ...

, Italy. In 1868 he was awarded a bachelor's degree from the '' Università di Modena'', then an engineering degree from the '' Politecnico di Milano''. Between 1868 and 1877 he worked as an assistant at the

Modena Modena (, ; ; ; ; ) is a city and ''comune'' (municipality) on the south side of the Po Valley, in the Province of Modena, in the Emilia-Romagna region of northern Italy. It has 184,739 inhabitants as of 2025. A town, and seat of an archbis ...

Observatory, teaching mathematics and physics at the ''Università di Modena''. He taught at

Naples Naples ( ; ; ) is the Regions of Italy, regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 908,082 within the city's administrative limits as of 2025, while its Metropolitan City of N ...

and then

Palermo Palermo ( ; ; , locally also or ) is a city in southern Italy, the capital (political), capital of both the autonomous area, autonomous region of Sicily and the Metropolitan City of Palermo, the city's surrounding metropolitan province. The ...

, where he also worked at the observatory. In 1890 he was named to the chair of astrophysics at the Università di Catania, and became director of the observatory on

Mount Etna Mount Etna, or simply Etna ( or ; , or ; ; or ), is an active stratovolcano on the east coast of Sicily, Italy, in the Metropolitan City of Catania, between the cities of Messina, Italy, Messina and Catania. It is located above the Conve ...

as well as the first director of the Catania Observatory. Between 1898 and 1900 he was named chancellor of the university. During his career he performed research into sunspots, and he participated in four

solar eclipse A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of Earth, totally or partially. Such an alignment occurs approximately every six months, during the eclipse season i ...

expeditions, leading the expeditions in 1905 and 1914. He was president of the ''Società degli Spettroscopisti Italiani'' and the ''Gioenia di Scienze Naturali di Catania''. He also served as vice president of the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

. He was elected President of the volcanology section of the International Union of Geodesy and Geophysics (IUGG) for the period 1919–1922.

Legacy

He discovered Ricco's Law, an important principle of

vision science Vision science is the scientific study of visual perception. Researchers in vision science can be called vision scientists, especially if their research spans some of the science's many disciplines. Vision science encompasses all studies of vision ...

. The crater Ricco on the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

is named after him, as is the asteroid 18462 Ricco. Ricco was also awarded the Janssen Medal in 1906 by the

French Academy of Sciences The French Academy of Sciences (, ) is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific method, scientific research. It was at the forefron ...

for his work in astrophysics. He was also awarded the Prix Jules Janssen of the Société astronomique de France (French Astronomical Society) in 1914. He died in

Rome Rome (Italian language, Italian and , ) is the capital city and most populated (municipality) of Italy. It is also the administrative centre of the Lazio Regions of Italy, region and of the Metropolitan City of Rome. A special named with 2, ...

, Italy.

References

On the History of the Palermo Astronomical Observatory

Riccò Annibale
biography. * * {{DEFAULTSORT:Ricco, Annibale 1844 births 1919 deaths Italian geophysicists Polytechnic University of Milan alumni 19th-century Italian astronomers 20th-century Italian astronomers People from Milan