Sentence:  After discovering "<WSD>planetoids</WSD>", bodies orbiting the Sun, even larger than Pluto's moon Charon ... the question of how Sedna and other <WSD>planetoids</WSD> came to be. 
Meaning of the word marked with <WSD> tags:  A larger, planetary, body in orbit around the Sun, such as Vesta or (candidate) dwarf planets such Eris or Sedna