Despite those beautiful pictures from the New Horizons spacecraft, Pluto continues to be the Rodney Dangerfield of space objects. The latest attack on it comes from a study the journal Icarus where astronomers present their evidence that the former planet and current dwarf planet is actually just a giant comet or, even worse, a giant dirty snowball made of billions of small comets held together by icy nitrogen. Will Pluto be reduced to being a frozen cosmic I-get-no-respect comic telling passing planets that it told its psychiatrist that every astronomer hates it and the shrink says “That can’t be true because every astronomer hasn’t seen you yet”?
“Using chemistry as a detective’s tool, we are able to trace certain features we see on Pluto today to formation processes from long ago. This leads to a new appreciation of the richness of Pluto’s ‘life story,’ which we are only starting to grasp.”
That spin on the Pluto’s-just-a-ball-of-comets theory comes from Dr. Christopher Glein of the Southwest Research Institute (SwRI) Space Science and Engineering Division in San Antonio, Texas, and co-author of the study. According to the press release, Glein and other astronomers got this radical idea not from Pluto itself but from another space object – Comet 67P/Churyumov–Gerasimenko – which was studied for over two years starting in 2014 by the Rosetta spacecraft. While looking at the Sputnik Planitia glacial area of Pluto in an attempt to determine why it had such a high concentration of nitrogen, Glein and his team had a Comet 67P-generted “Eureka!” moment.
“We found an intriguing consistency between the estimated amount of nitrogen inside the glacier and the amount that would be expected if Pluto was formed by the agglomeration of roughly a billion comets or other Kuiper Belt objects similar in chemical composition to 67P, the comet explored by Rosetta.”
From that, they developed the “giant comet’ cosmochemical model of Pluto formation.” How did it happen? They’re not sure. In fact, they’re not even sure how much nitrogen Pluto had to start with, how much it leaked into space or why it has so little carbon dioxide. Is it buried under its surface? Was it destroyed by an ancient ocean? And then there’s the big question … how did billions of comets join together to form whatever it is we call Pluto?
“When Pluto was born, it was so ugly, the rest of the universe slapped the Big Bang.”
So what exactly is Pluto? Until more research is conducted and more space probes reach it, International Comet Quarterly (who knew comets had a quarterly publication?) had this to say:
“And, yes, it might be that we will want to consider placing Pluto in different categories, such as (minor) planet and comet. Such "dual status" already exists for some comets and minor planets, which are given formal numbers and names in both kinds of catalogues.”
Here’s an idea. Let’s show Pluto some respect by giving it a name and category all of its own … the Rodney.
“I looked up my cosmic family tree and found three dog stars using it.”