The word 'planet' is derived from a Greek word that means 'wanderer'. It referred to the fact that several of the lights in the sky at night seemed to move around with respect to the others, which otherwise marched across the heavens in an orderly fashion during the passing of the seasons.
The term was used for centuries before the discovery of Pluto, and even before the discovery of the fact that the Earth was round.
Given its original meaning, the classification of Earth as a planet is not correct. Because the Earth cannot be seen as a point of light from its own surface and can therefore not wander.
Why don't we go back to first principals on all this and just start classifying Solar System objects in a similar way to that used for stars, for which we use luminosity, spectra, size, color, etc.. Solar system objects have different properties against which they can be grouped, but why not?
The term was used for centuries before the discovery of Pluto, and even before the discovery of the fact that the Earth was round.
Given its original meaning, the classification of Earth as a planet is not correct. Because the Earth cannot be seen as a point of light from its own surface and can therefore not wander.
Why don't we go back to first principals on all this and just start classifying Solar System objects in a similar way to that used for stars, for which we use luminosity, spectra, size, color, etc.. Solar system objects have different properties against which they can be grouped, but why not?