4 ms·
"Planet X" was used before Pluto was discovered. The X didn't mean 10. In fact, Pluto was thought to be Planet X before they realised it was much, much smaller
by globular-toast 2y ago
"Planet X" was used before Pluto was discovered. The X didn't mean 10. In fact, Pluto was thought to be Planet X before they realised it was much, much smaller than that.
- yellowapple 2y agoThe people now calling it Planet 9 instead of Planet X, as in the article, evidently didn't get that memo.