Gonzalo Tancredi (born 8 March 1963) is an

Uruguayan 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 ...

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 full professor in the Department of Astronomy at the

University of the Republic 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 ...

Montevideo Montevideo () is the capital and 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 . Montevideo is situated on the southern co ...

, Uruguay. He is an active member of the

International Astronomical Union 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, outreac ...

(IAU) and investigator at Los Molinos Observatory. His 2010 evaluation of potential dwarf planets was considered by the IAU, though never acted on. The Themistian asteroid 5088 Tancredi has been named after him.

Definition of planet

In 2006, Tancredi was one of a number of dissenters at the IAU'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 ...

and Ceres among the planets, Tancredi with his Uruguayan colleague

Julio Ángel Fernández Julio Ángel Fernández Alves (born 5 April 1946) is a Uruguayan astronomer and teacher, member of the department of astronomy at the Universidad de la República in Montevideo. He is also a member of PEDECIBA, (the program for development of ba ...

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 System Capitalization 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 ...

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 ...

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 ...

s."

References

External links

Gonzalo Tancredi – Departamento de Astronomía, Instituto de Física, Facultad de Ciencias, Montevideo, URUGUAY

1963 births Living people Uruguayan astronomers University of the Republic (Uruguay) faculty {{Uruguay-scientist-stub