Post by Centaur on Aug 24, 2006 11:19:28 GMT -6
Pluto has been officially stricken from the IAU’s list of planets: www.iau2006.org/mirror/www.iau.org/iau0603/index.html
I applaud the new definition of a planet. Let’s remember that the term was coined by our ancestors in reference to star-like objects that appear to wander relative to the so-called fixed stars. Invisible objects due to small size or great distance were understandably not included. In particular, the term did not apply to unseen bodies circling fixed stars. Earth was added to the set following an historic debate regarding heliocentricity. The later discovered Uranus and Neptune unquestionably had the size and orbital characteristics of planets.
In 1930 some astronomers were looking for a planet. A high school graduate was assigned the tedious chore of comparing photographs. When a distant object was discovered, it was deemed a planet with little question. Had astronomers thought more deeply they may have investigated the matter more fully leading to the discovery of what might have been called the Tombaugh belt rather than the Kuiper Belt.
The characteristics and methods of formation of other bodies in the solar system seem to mandate classes of their own. Regarding bodies circling fixed stars, the term extra-solar planets may be sufficient for that set, although a new term could be devised.
It would have been simplest if the IAU had defined the set of planets as Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus & Neptune. Apparently they feel that defining the set by its properties provides justification. I suspect that very soon the simple naming of the members of the set will be deemed sufficient, especially for fourth grade textbooks.
Early in the nineteenth century school children were taught that Ceres was one of the planets. A half-century later, astronomers scratched it from the list, and teachers dutifully complied. I suspect that the public will stop referring to Pluto as one of the major planets much sooner than some are predicting.
I applaud the new definition of a planet. Let’s remember that the term was coined by our ancestors in reference to star-like objects that appear to wander relative to the so-called fixed stars. Invisible objects due to small size or great distance were understandably not included. In particular, the term did not apply to unseen bodies circling fixed stars. Earth was added to the set following an historic debate regarding heliocentricity. The later discovered Uranus and Neptune unquestionably had the size and orbital characteristics of planets.
In 1930 some astronomers were looking for a planet. A high school graduate was assigned the tedious chore of comparing photographs. When a distant object was discovered, it was deemed a planet with little question. Had astronomers thought more deeply they may have investigated the matter more fully leading to the discovery of what might have been called the Tombaugh belt rather than the Kuiper Belt.
The characteristics and methods of formation of other bodies in the solar system seem to mandate classes of their own. Regarding bodies circling fixed stars, the term extra-solar planets may be sufficient for that set, although a new term could be devised.
It would have been simplest if the IAU had defined the set of planets as Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus & Neptune. Apparently they feel that defining the set by its properties provides justification. I suspect that very soon the simple naming of the members of the set will be deemed sufficient, especially for fourth grade textbooks.
Early in the nineteenth century school children were taught that Ceres was one of the planets. A half-century later, astronomers scratched it from the list, and teachers dutifully complied. I suspect that the public will stop referring to Pluto as one of the major planets much sooner than some are predicting.
