Home > Giuseppe Piazzi

On January 1, 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 2d 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 4th, 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 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 to compute its orbit with existing methods, but the renowned 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 planetA planet (from the Greek , planetes or "wanderers") is a body of considerable mass that orbits a star and that produces very little or no energy through nuclear fusion. Prior to the 1990s only nine were known (all of them in our own solar system); as of 3. It was also almost exactly where the Titius-Bode lawThe Titius-Bode law (or Bode's law is the observation that orbits of planets in the solar system closely follow a simple geometric rule. It was discovered in 1766 by Johann Daniel Titius and "published" (without attribution) in 1772 by Johann Elert Bode, predicted a planet would be.

Piazzi named it "Ceres Ferdinandea", after the Classical Greek and Sicilian goddess of grainFor other uses, see Ceres (disambiguation). Ceres in Roman mythology, equivalent to the Greek Demeter (which see for more details), daughter of Saturn and Rhea, wife-sister of Jupiter, mother of Proserpina by Jupiter, sister of Juno, Vesta, Neptune and Pl and King Ferdinand IV of Naples and SicilySicily Sicilia in Italian) is an autonomous region of Italy and the largest island in the Mediterranean Sea, with an area of 25,700 sq. 1 million inhabitants. Towns and Cities Sicily's principal cities include the regional capital Palermo, together with t. 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.

In 1923, the 1000th asteroid to be discovered was named Piazzia in his honour. More recently, a large albedo feature, probably a crater, imaged by the Hubble Space Telescope on Ceres, has been informally named 'Piazzi'.