Discovery of an asteroid

1801 Discovery of an asteroid

The book of science

Tom Sharp

Giuseppe Piazzi, Carl Friedrich Gauss astronomy Discovery of an asteroid

Discovery of an asteroid

Hole in the sky


A beautiful color photo of Ceres from NASA’s Hubble Space Telescope, in which each pixel represents 18 kilometers, shows its jewel-like surface. (See also the original on the HubbleSite.) The beauty of the object in space increases my admiration of the goddess Ceres.

Piazzi’s discovery is a good example of a disciplined accident. Like making an informed decision, Piazzi would not have recognized the uniqueness of this spot of light without intense concentration and keen skills. The beauty of his instrument was also a factor; the Science Photo Library has an illustration of Jesse Ramsden’s altazimuthal circle in Palermo.

An object in space must have objective characterstics to be regarded as a planet, or people would be discovering new planets all the time; I might want to discover my own planet. A planet must be spherical, rotate its sun in a circular orbit, and not be a satellite. Too bad for Ceres and Pluto, the International Astronomical Union now says that a planet must clear the neighborhood of its orbit.

In the biographies, Piazzi is characterized as uncertain whether Ceres was a star, a planet, or a comet, but I much prefer Piazzi’s thoughtful and cautious attitude, and the openness of his mind, compared to Johann Elert Bode who claimed (sight unseen) that Piazzi had found exactly what Bode expected.

As an American perhaps, I take a certain delight in repeating the name “Guiseppi,” by which I do not mean to slight any of his other names (six names, each with three syllables).

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