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
See also in The book of science:
Readings on wikipedia:
You can find lots of information about Giuseppe Piazzi: