largest known asteroid

largest known asteroid

Ceres, dwarf planet and largest known asteroid in the asteroid belt and the first asteroid to be discovered. Ceres was found, serendipitously, by the Italian astronomer Giuseppe Piazzi of the PalermoObservatory on Jan. 1, 1801. Additional observations of the object by Piazzi were cut short by illness, but Ceres was recovered on Jan. 1, 1802, by the German Hungarian astronomer Franz von Zach, using anorbit calculated by the German mathematician Carl Friedrich Gauss. largest known asteroid-Ceres was named after the ancient Roman grain goddess and the patron goddess of Sicily, thus beginning a long-standing tradition of naming main-belt asteroids after female characters from Greco-Roman mythology.

largest known asteroid

 

The Cererian surface is probably a mixture of water ice and various hydrated minerals such as carbonates and clays. It appears to be differentiated into a rocky core and icy mantle,and may harbour an ocean of liquid water under its surface. From Earth, the apparent magnitude of Ceres ranges from 6.7 to 9.3, and hence even at its brightest it is still too dim to be seen with the naked eye except under extremely dark skies.

largest known asteroid

Ceres revolves around the Sun once in 4.61 Earth years in a nearly circular, moderately inclined (10.6°) orbit at a mean distance of 2.77 astronomical units (AU; about 414 million km [257 million miles]). Although it—and the next two asteroids discovered, Pallas and Juno—are located near the distance predicted by Bode’s law for the “missing” planet between Mars and Jupiter, most asteroids found subsequently are not so located, and so the agreement with this “law” appears to be coincidental.

it was January, 1801, a new year and a new century and Giuseppe Piazzi, a monk in Sicily and the founding director of the Palermo Astronomical Observatory, was on the verge of discovering a new celestial object. He was continuing to make his regular nightly observations when something caught his eye. He described it in his journal this way, “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.”

When the object did not appear where it should on January 2, Piazzi began to doubt his observations until the thought occurred to him that perhaps he was seeing a “new star *.” It wasn’t until the third of January when his “suspicion was converted into certainty, being assured it was not a fixed star.” Finally, on the fourth night of his observations, he had “the satisfaction to see it had moved at the same rate as on the preceding days.”

Although he was certain he had discovered a new planet, Piazzi announced it as a newly discovered comet. He wasn’t able to observe it much longer, as its orbit carried it into the glare of the sun. Later, using mathematician Carl Friedrich Gauss’s newly developed method of orbit calculation, astronomers were able to locate it again. Combined with the the Titius-Bode law which predicted a planet should be located in that area, the new object was declared a new planet. Piazzi named it “Ceres Ferdinandea,” after the Roman and Sicilian goddess of grain and King Ferdinand IV of Naples and Sicily.

 

largest known asteroid

In fairly short order, over the next few years, three other objects were discovered in a roughly similar orbit; Pallas in 1802, Juno in 1804 and Vesta in 1807. In fact, by the end of the century, several hundred had been found. By that time, it Ceres’s designation had been changed from planet to a new term, asteroid.

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