Pluto is not a giant comet!

Within the past week, you may have seen reports of a study that some scientists say indicates Pluto is actually a giant comet that was formed by the aggregation of billions of comets. This is not true! What the study actually found is that both Sputnik Planitia, the left side of Pluto's heart feature, and Comet 67P/Churyumov-Gerasimenko, both were found to have the same isotope of nitrogen on their surfaces. While this is true and suggests they may originate in the same region of the solar system, it does not mean Pluto is a giant comet! In this case, people erroneously drew a conclusion without sufficient data to confirm that conclusion.

Below is a good article by planetary scientist Philip Metzger explaining why Pluto is not a giant comet.

Icy Worlds and Stars with Long Hair - Philip Metzger: Are icy worlds like Pluto just comets because they're made of ice? This post looks at what planets made of and looks at the amazing insides of icy worlds.