Italian Catholic priest of the Theatine order, mathematician, and astronomer
Giuseppe Piazzi
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Born
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1746-07-16
)
16 July 1746
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Died
| 22 July 1826
(1826-07-22)
(aged 80)
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Nationality
| Italian
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Known for
| Discovery of the first dwarf planet,
Ceres
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Awards
| Lalande Prize
(1803)
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Scientific career
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Fields
| Astronomy
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Institutions
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Giuseppe Piazzi
(
PYAHT
-see
,
[1]
Italian:
[d?u?z?ppe
?pjattsi]
; 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. Vaiana
.
[2]
He is perhaps most famous for his discovery of the first dwarf planet,
Ceres
.
Early life
[
edit
]
No documented account of Piazzi's scientific education is available in any of the biographies of the astronomer, even in the oldest ones. Piazzi certainly did some studies in
Turin
, quite likely attending
Giovan Battista Beccaria
's lessons. In the years 1768?1770 he was resident at the Theatines' Home in
S. Andrea della Valle
, Rome, while studying Mathematics under
Francois Jacquier
.
In July 1770, he took the chair of Mathematics at the
University of Malta
.
In December 1773, he moved to
Ravenna
as "prefetto degli studenti" and lecturer in Philosophy and Mathematics at the Collegio dei Nobili, where he stayed until the beginning of 1779. After a short period spent in
Cremona
and in Rome, in March 1781 Piazzi moved to
Palermo
as lecturer in Mathematics at the
University of Palermo
(at the time known as "Accademia de' Regj Studi").
He kept this position until 19 January 1787, when he became Professor of Astronomy. Almost at the same time, he was granted permission to spend two years in Paris and London, to undergo some practical training in astronomy and also to get some instruments to be specially built for the Palermo Observatory, whose foundation he was in charge of.
In the period spent abroad, from 13 March 1787 until the end of 1789, Piazzi became acquainted with the major French and English astronomers of his time and was able to have the famous altazimuthal circle made by
Jesse Ramsden
, one of the most skilled instrument-makers of the 18th century.
The circle was the most important instrument of the Palermo Observatory, whose official foundation took place on 1 July 1790.
In 1817,
King Ferdinand
put Piazzi in charge of the completion of the
Capodimonte (Naples) Observatory
, naming him General Director of the Naples and Sicily Observatories.
Astronomy career
[
edit
]
Star cataloguing
[
edit
]
He supervised the compilation of the Palermo Catalogue of stars, containing 7,646 star entries with unprecedented precision,
[3]
including the star names "
Garnet Star
" from
Herschel
, and the
original
Rotanev
and
Sualocin
. The work to observe the sky methodically. The catalogue wasn't finished for first edition publication until 1803, with a second edition in 1814.
Spurred by the success discovering Ceres (see below), and in the line of his catalogue program, Piazzi studied the proper motions of stars to find parallax measurement candidates. One of them,
61 Cygni
, was specially appointed as a good candidate for measuring a parallax, which was later performed by
Friedrich Wilhelm Bessel
.
[5]
The star system
61 Cygni
is sometimes still called variously
Piazzi's Flying Star
and
Bessel's Star
.
The dwarf planet Ceres
[
edit
]
Piazzi discovered
Ceres
. On 1 January 1801 Piazzi discovered a "stellar object" that moved against the background of
stars
. At first he thought it was a fixed star, but once he noticed that it moved, he became convinced it was a planet, or as he called it, "a new star".
In his journal, he wrote:
The light was a little faint, and of the colour of
Jupiter
, but similar to many others which generally are reckoned of the eighth
magnitude
. Therefore I had no doubt of its being any other than a fixed star. In the evening of the second I repeated my observations, and having found that it did not correspond either in time or in distance from the zenith with the former observation, I began to entertain some doubts of its accuracy. I conceived afterwards a great suspicion that it might be a new star. The evening of the third, my suspicion was converted into certainty, being assured it was not a fixed star. Nevertheless before I made it known, I waited till the evening of the fourth, when I had the satisfaction to see it had moved at the same rate as on the preceding days.
In spite of his assumption that it was a planet, he took the conservative route and announced it as a
comet
. In a letter to astronomer
Barnaba Oriani
of
Milan
he made his suspicions known in writing:
I have announced this star as a comet, but since it is not accompanied by any nebulosity and, further, since its movement is so slow and rather uniform, it has occurred to me several times that it might be something better than a comet. But I have been careful not to advance this supposition to the public.
He was not able to observe it long enough as it was soon lost in the glare of the
Sun
. Unable to compute its
orbit
with existing methods, the mathematician
Carl Friedrich Gauss
developed a new method of orbit calculation that allowed astronomers to locate it again. After its orbit was better determined, it was clear that Piazzi's assumption was correct and this object was not a comet but more like a small
planet
. Coincidentally, it was also almost exactly where the
Titius?Bode law
predicted a planet would be.
Piazzi named it "Ceres Ferdinandea," after the
Roman
and Sicilian
goddess of grain
and
King Ferdinand IV
of
Naples
and
Sicily
. The Ferdinandea part was later dropped for political reasons.
Ceres
turned out to be the first, and largest, of the
asteroids
existing within the
asteroid belt
. Ceres is today called a
dwarf planet
.
Posthumous honours
[
edit
]
Born in Italy and named in his honour was the astronomer
Charles Piazzi Smyth
, son of the astronomer
William Henry Smyth
. In 1871, a memorial statue of Piazzi sculpted by
Costantino Corti
was dedicated in the main plaza of his birthplace, Ponte. In 1923, the 1000th asteroid to be numbered was named
1000 Piazzia
in his honour.
[6]
The lunar crater
Piazzi
was named after him in 1935. More recently, a large
albedo
feature, probably a
crater
, imaged by the
Hubble Space Telescope
on Ceres, has been informally named
Piazzi
.
Works
[
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]
See also
[
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]
References
[
edit
]
Sources
[
edit
]
- Clifford Cunningham, Brian Marsden, Wayne Orchiston. (2011) "Giuseppe Piazzi: the controversial discovery and loss of Ceres in 1801."
Journal for the History of Astronomy
, Volume 42.
- Cunningham, C. J. (2001).
The First Asteroid
. Star Lab Press.
ISBN
978-0-9708162-2-1
.
- Fodera Serio, G.; Manara, A.; Sicoli, P. (2002).
"Giuseppe Piazzi and the Discovery of Ceres"
(PDF)
. In W. F. Bottke Jr.; A. Cellino; P. Paolicchi; R. P. Binzel (eds.).
Asteroids III
. Tucson, Arizona:
University of Arizona Press
. pp. 17?24.
- Fox, William (1913).
"Giuseppe Piazzi"
. In Herbermann, Charles (ed.).
Catholic Encyclopedia
. New York: Robert Appleton Company.
External links
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