Planetary confusion -- why astronomers keep changing what it means to be a planet
December 15, 2019
(The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.)
Christopher Palma, Pennsylvania State University
(THE CONVERSATION) As an astronomer, the question I hear the most is why isn't Pluto a planet anymore? More than 10 years ago, astronomers famously voted to change Pluto's classification. But the question still comes up.
When I am asked directly if I think Pluto is a planet, I tell everyone my answer is no. It all goes back to the origin of the word "planet." It comes from the Greek phrase for "wandering stars." Back in ancient t...