How large should a planet be to be considered a major planet in our solar system? By major, I am taking both the astronomical and astrological viewpoint here.

Yes size does matter in both astronomy and astrology and there must obviously be a cut-off point in tems of minimum size, otherwise there would simply be too many bodies out there vying for official planethood.

In 2006 the International Astronomical Union established a criteria or set of rules for planethood, namely that it must orbit the Sun, be of large enough size to become round, and have orbital dominance, leaving 8 bodies - Mercury, Venus, Earth. Mars, Jupiter, Saturn, Uranus, and Neptune as legitimate planets. Pluto, Eris, and smaller round bodies fall into the category of dwarf planets. That is the astronomical view.

In astrology, which is geocentric rather than heliocentric, there are currently ten recognized bodies - Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto, with allegedly two more awaiting recognition.

Any self-respecting astrologer knows the power of Pluto accepting it as a full fledged planet despite its tiny size. It's large moon Charon makes it a double planet giving Pluto that extra whack or power. Earth or Terra works via the Ascendant or Rising sign, and the Sun and Moon have always been considered as "planets" by the ancients.

If we include Sun, Moon, Earth, and Pluto along with the other bodies recognized by astronomy we have a total of eleven official or major bodies in our system. Astrology requires at least twelve bodies - one for every sign. So one more needs to be discovered, recognized, or added.

In 2005, astronomers discovered Xena/Eris beyond Pluto and initially dubbed it the 10th planet. Eris is roughly the same size as Pluto but twice as far in distance. Astrologers are currently evaluating as to whether Eris should acquire planetary status on par with Pluto and the others.

All of these twelve bodies have diameters of 1400 miles or greater, and the variation is HUGE, from the dwarfs (Pluto and Eris) to the inner planets (Moon, Mercury, Venus, Earth, Mars) to the outer giants (Jupiter, Saturn, Uranus, Neptune) to our Sun. Whether astronomers have their correct sizes is debatable but we will give them the doubt.

So should Pluto, currently the smallest "planet" at 1477 miles or 2377 kilometers diameter, be the lower size limit for accepting new planets? Personally, I believe it should be 1200 miles or 1931 kilometers. More precisely, it should be 1199.33 miles or 1930.134 kilometers(which equates with the Feb.18,1930 discovery date of Pluto). This would bring in Eris and exclude all the other wannabe dwarfs, as well as Chiron and the centaurs from the big planet club.

No doubt the smaller bodies have their supporting and detracting roles to play in the scheme of things, but they will never be on par with the main player planets. I may be wrong about the 1200 mile lower diameter limit, but I feel strongly about it, and am just throwing it out there for your consideration.