Re: Space Question
I thought the X was originally a roman numeral for the number 10. Thus, the tenth planet.
I don’t think of Pluto as being a planet. I see that small world as being the largest known comet. I hate hearing them call Pluto/Chiron a double planet.
Ceres was actually called a planet at one time. It is not much smaller than Pluto.
Looking inward, for a short time scientist thought they discovered a planet closer to Sun than Mercury. They call this planet Vulcan. I believe they claimed they spotted it cross the Sun twice. Then it was never seen again.