Poor Pluto. Until recently, it was the ninth planet in our solar system, located way beyond Neptune. Then in 2006 it was demoted to a dwarf planet. Now something else is claiming to be the real ninth planet. Caltech Astronomers Mike Brown and Konstantin Batygin have mathematically postulated the existence of a huge body with an elliptical orbit near the Kuiper Belt that they are calling Planet Nine.
Some good research paper topics are to write about past and present planetary discovery. Read more