A group of scientists have written a paper
https://www.sciencedirect.com/science/article/pii/S0019103521004206
which provides a rationale for calling Pluto a planet again. However, it will have lots of company if their recommendation were adopted.
The paper claims that, down to about 1857, after the Copernican revolution,
the normal meaning of the term 'planet' among astronomers included
both the primary planets and the secondary planets - the latter class
including both the Moon and the Galilean satellites of Jupiter.
The idea of restricting the term 'planet' to primary planets, and then
to _major_ primary planets, is claimed to have its roots in a folk
taxonomy influenced by astrology and theology, outside of the
scientific world, and, thus, this definition isn't really scientifically useful, it is claimed.
John Savard
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