Barnaba Oriani FRS FRSE (17 July 1752 – 12 November 1832) was an Italian

priest A priest is a religious leader authorized to perform the sacred rituals of a religion, especially as a mediatory agent between humans and one or more deities. They also have the authority or power to administer religious rites; in partic ...

geodesist Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equival ...

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

and

scientist A scientist is a person who conducts scientific research to advance knowledge in an area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, philosophers engaged in the philosoph ...

Life

Oriani was born in Garegnano (now part of

Milan Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city h ...

), the son of a mason, and died in Milan. After getting his elementary education in Garegnano, he went on to study at the College of San Alessandro in Milan, under the tutelage and with the support of the Order of Barnabites,Students for the Exploration and Development of Space
/ref> which he later joined. After completing his studies in the

humanities Humanities are academic disciplines that study aspects of human society and culture. In the Renaissance, the term contrasted with divinity and referred to what is now called classics, the main area of secular study in universities at the t ...

physical Physical may refer to: *Physical examination In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally co ...

and

mathematical Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...

sciences, philosophy, and

theology Theology is the systematic study of the nature of the divine and, more broadly, of religious belief. It is taught as an academic discipline, typically in universities and seminaries. It occupies itself with the unique content of analyzing the ...

, he was ordained a priest in 1775. When

Napoleon I Napoleon Bonaparte ; it, Napoleone Bonaparte, ; co, Napulione Buonaparte. (born Napoleone Buonaparte; 15 August 1769 – 5 May 1821), later known by his regnal name Napoleon I, was a French military commander and political leader who ...

established the Republic of Lombardy, Oriani refused to swear an oath against the monarchy, and the new republican government modified the oath of allegiance on his behalf. He was retained in his position at the observatory and was made president of the commission appointed to regulate the new system of

weights and measures A unit of measurement is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can be expressed as a multi ...

. When the republic became a Napoleonic kingdom, Oriani was awarded the

Iron Crown The Iron Crown ( lmo, Corona Ferrea de Lombardia; it, Corona Ferrea; la, Corona Ferrea) is a relic and may be one of the oldest royal insignia of Christendom. It was made in the Early Middle Ages, consisting of a circlet of gold and jewels fit ...

and the

Legion of Honour The National Order of the Legion of Honour (french: Ordre national de la Légion d'honneur), formerly the Royal Order of the Legion of Honour ('), is the highest French order of merit, both military and civil. Established in 1802 by Napoleon ...

, was made a

count Count (feminine: countess) is a historical title of nobility in certain European countries, varying in relative status, generally of middling rank in the hierarchy of nobility. Pine, L. G. ''Titles: How the King Became His Majesty''. New York: ...

and senator, and was appointed to measure the

arc of the meridian In geodesy and navigation, a meridian arc is the curve between two points on the Earth's surface having the same longitude. The term may refer either to a segment of the meridian, or to its length. The purpose of measuring meridian arcs is to ...

between the zeniths of

Rimini Rimini ( , ; rgn, Rémin; la, Ariminum) is a city in the Emilia-Romagna region of northern Italy and capital city of the Province of Rimini. It sprawls along the Adriatic Sea, on the coast between the rivers Marecchia (the ancient ''Ariminu ...

and

Rome , established_title = Founded , established_date = 753 BC , founder = King Romulus (legendary) , image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg , map_caption ...

. Oriani was a devoted friend of the

Theatine The Theatines officially named the Congregation of Clerics Regular ( la, Ordo Clericorum Regularium), abreviated CR, is a Catholic order of clerics regular of Pontifical Right for men founded by Archbishop Gian Pietro Carafa in Sept. 14, 1524. I ...

monk

Giuseppe Piazzi Giuseppe Piazzi ( , ; 16 July 1746 – 22 July 1826) was an Italian Catholic priest of the Theatine order, mathematician, and astronomer. He established an observatory at Palermo, now the '' Osservatorio Astronomico di Palermo – Giuseppe S ...

, the discoverer of

Ceres Ceres most commonly refers to: * Ceres (dwarf planet), the largest asteroid * Ceres (mythology), the Roman goddess of agriculture Ceres may also refer to: Places Brazil * Ceres, Goiás, Brazil * Ceres Microregion, in north-central Goiás ...

. Oriani and Piazzi worked together for thirty-seven years, cooperating on many astronomical observations.

Astronomy

Given his strong interest in astronomy, Oriani was appointed on the staff of the Observatory of Brera in Milan in 1776, becoming assistant astronomer in 1778 and director in 1802. In 1778 he began publishing various in-depth dissertations on astronomical objects, the ''Effemeridi di Milano'' ( Ephemerides of Milan). A very capable astronomer, Oriani's work began to attract considerable attention. His research in the areas of astronomic refraction, the

obliquity of the ecliptic In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and o ...

, and orbital theory were of considerable noteworthiness in themselves; but his greatest achievement was his detailed research of the planet

Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus ( Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars), grandfather of Zeus (Jupiter) and father of ...

, which had been discovered by

Sir William Herschel Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline H ...

in 1781. Oriani devoted significant time to observations of Uranus, calculating its orbital properties which he published as a booklet of tables in 1793.Alexandro Malaspina Research Centre
After others had shown that Uranus was not on a parabolic orbit but rather in a roughly circular orbit, he calculated the orbit in 1783. In 1789, Oriani improved his calculations by accounting for the gravitational effects of

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...

and Saturn. In addition to his continual contributions to the ''Effemeridi'', he published a series of memoirs on

spherical trigonometry Spherical trigonometry is the branch of spherical geometry that deals with the metrical relationships between the sides and angles of spherical triangles, traditionally expressed using trigonometric functions. On the sphere, geodesics are grea ...

: the ''Memorie dell' Istituto Italiano'', 1806–10, and the ''Istruzione suelle misure e sui pesi'', 1831. For his work in astronomy, Oriani was honoured by naming asteroid 4540 "Oriani". This asteroid had been discovered at the

Osservatorio San Vittore The San Vittore Observatory ( it, Osservatorio San Vittore, obs. code: 552) is an astronomical observatory in Bologna, Italy. In the years from 1975 to 1981 the San Vittore Observatory (Bologna) Italy participated to the International Pl ...

Bologna, Italy Bologna (, , ; egl, label=Emilian language, Emilian, Bulåggna ; lat, Bononia) is the capital and largest city of the Emilia-Romagna region in Northern Italy. It is the seventh most populous city in Italy with about 400,000 inhabitants and 1 ...

on 6 November 1988.

Oriani's theorem

In ''De refractionibus astronomicis'', Oriani showed that astronomical refraction could be expanded as a series of odd powers of (tan Z), where Z is the observed

zenith distance The zenith (, ) is an imaginary point directly "above" a particular location, on the celestial sphere. "Above" means in the vertical direction (plumb line) opposite to the gravity direction at that location (nadir). The zenith is the "highest" ...

. Such a series had previously been derived by J. H. Lambert, who dropped all but the first term. However, Oriani investigated the higher terms, and he found that neither of the first two terms depended on the structure of the atmosphere. The

series expansion In mathematics, a series expansion is an expansion of a function into a series, or infinite sum. It is a method for calculating a function that cannot be expressed by just elementary operators (addition, subtraction, multiplication and divisi ...

he obtained was effective at up to 85 degrees from the zenith. Unlike previous approximations, however, Oriani's two-term expression did not depend on a hypothesis regarding atmospheric temperature or air density in relation to

altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

. Thus, the effects of atmospheric curvature are only dependent upon the temperature and pressure ''at the location of the observer''. Oriani's theorem explains why Cassini's uniform-density model works well except near the horizon—the atmospheric refraction from the zenith to a zenith distance of 70° is not dependent on the details of the distribution of the gas.

References

{{DEFAULTSORT:Oriani, Barnaba 1752 births 1832 deaths Clergy from Milan 18th-century Italian astronomers 19th-century Italian astronomers Catholic clergy scientists Fellows of the Royal Society Scientists from Milan

Life

Astronomy

Oriani's theorem

See also

References