Julio Ángel Fernández Alves (born 5 April 1946) is a

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

an astronomer and teacher, member of the department of astronomy at the

Universidad de la República The University of the Republic ( es, Universidad de la República, sometimes ''UdelaR'') is Uruguay's oldest public university. It is by far the country's largest university, as well as the second largest public university in South America and t ...

Montevideo Montevideo () is the Capital city, capital and List of cities in Uruguay, largest city of Uruguay. According to the 2011 census, the city proper has a population of 1,319,108 (about one-third of the country's total population) in an area of . M ...

. He is also a member of PEDECIBA, (the program for development of basic sciences in Uruguay), and the Uruguayan Society of Astronomy. From 2005 to 2010, he was the Dean of the Universidad de la Republica's Faculty of Sciences. The asteroid 5996 Julioangel, discovered in 1983, was named after him. He is an active researcher of the Researchers National System of Uruguay. Fernandez is member of the

National Academy of Sciences of the United States The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...

Kuiper belt

In 1980, in his paper ''On the existence of a comet belt beyond Neptune'', Fernández proposed that

periodic comet Periodic comets (also known as short-period comets) are comets with orbital periods of less than 200 years or that have been observed during more than a single perihelion passage (e.g. 153P/Ikeya–Zhang). "Periodic comet" is also sometimes used ...

s arrived too frequently into the inner Solar System to be accounted for solely by having arrived from the

Oort cloud The Oort cloud (), sometimes called the Öpik–Oort cloud, first described in 1950 by the Dutch astronomer Jan Oort, is a theoretical concept of a cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from 2 ...

, and that a trans-Neptunian belt of comets at around 50 AU would be required to explain them. Subsequent computer models by Martin Duncan, Tom Quinn and

Scott Tremaine Scott Duncan Tremaine (born 1950) is a Canadian-born astrophysicist. He is a fellow of the Royal Society of London, the Royal Society of Canada and the National Academy of Sciences. Tremaine is widely regarded as one of the world's leading as ...

in Canada supported the view, and led eventually to the discovery of the

Kuiper belt The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...

. Many astronomers, including

David Jewitt David Clifford Jewitt (born 1958) is a British-American astronomer who studies the Solar System, especially its minor bodies. He is based at the University of California, Los Angeles, where he is a Member of the Institute for Geophysics and Pl ...

, who discovered the belt, believe that Fernández deserves more credit than anyone else, including

Gerard Kuiper Gerard Peter Kuiper (; ; born Gerrit Pieter Kuiper; 7 December 1905 – 23 December 1973) was a Dutch astronomer, planetary scientist, selenographer, author and professor. He is the eponymous namesake of the Kuiper belt. Kuiper is c ...

, for predicting its existence. He has subsequently published many papers on the

trans-Neptunian A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has a semi-major axis of 30.1 astronomical units (au). Typically, ...

population.

Definition of planet

In 2006, Fernández was one of a number of dissenters at the

IAU The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...

's meeting to establish the first definition of "planet. " As an alternative to the IAU's draft proposal, which had included

Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the S ...

, its moon

Charon In Greek mythology, Charon or Kharon (; grc, Χάρων) is a psychopomp, the ferryman of Hades, the Greek underworld. He carries the souls of those who have been given funeral rites across the rivers Acheron and Styx, which separate the wo ...

and

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 ...

among the planets, Fernández with his Uruguayan colleague

Gonzalo Tancredi Gonzalo Tancredi (born 8 March 1963) is an Uruguayan astronomer and full professor in the Department of Astronomy at the University of the Republic in Montevideo, Uruguay. He is an active member of the International Astronomical Union (IAU) and i ...

proposed a definition where they reserved the term "

planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...

" only for those objects in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

which had cleared their neighbourhoods of

planetesimal Planetesimals are solid objects thought to exist in protoplanetary disks and debris disks. Per the Chamberlin–Moulton planetesimal hypothesis, they are believed to form out of cosmic dust grains. Believed to have formed in the Solar System a ...

s, describing those objects which had not cleared their orbits yet retained a spherical shape as "planetoids." The IAU's final definition incorporated much of Fernández and Tancredi's proposal, though the objects were christened "

dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to p ...

s." The event originated the word "Plutoed," which was selected as the "word of the year 2006" by the

American Dialect Society The American Dialect Society (ADS), founded in 1889, is a learned society "dedicated to the study of the English language in North America, and of other languages, or dialects of other languages, influencing it or influenced by it." The Society ...

Books

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References

{{DEFAULTSORT:Fernandez, Julio Angel Uruguayan astronomers People from Montevideo Uruguayan scientists Uruguayan people of Spanish descent 1946 births Living people University of the Republic (Uruguay) faculty Foreign associates of the National Academy of Sciences