“It's the most geologically active planet besides the Earth. There are flowing glaciers (and) moving mountains. It is possible, at least possible, that Pluto might have life,” Metzger said.
But little Pluto was reduced to a "dwarf planet" in 2006 when the International Astronomical Union voted that it wasn't big enough to clear debris from its orbit.
"I think, unfortunately, the textbooks have short-changed Pluto and the entire solar system,” Metzger said.
Metzger and his team of researchers from Johns Hopkins and the Planetary Science Institute researched 200 years of data analyzing the "clearing of orbit" criteria for a planet, and found only one study in 1802 used that definition and it was later disproved.
"They didn't bother to explain what they mean by clearing orbit, and taking it literally, it's true. No planet clears its orbit, so therefore there are no planets,” Metzger said.
For scientists, icy Pluto is a hot debate.
Thousands have chimed in on both sides on social media about Metzger’s research.
For Metzger though, the problem isn't Pluto, it's that defining it came down to a vote based on opinions.
"When we published this paper, the outpouring of public interest was amazing, everybody is saying, ‘Yeah, save Pluto! We want our Pluto back!’” he said.
Metzger’s work was peer-reviewed and will be published in the scientific journal Icarus.
Meanwhile, the two scientists who self-claim they "killed Pluto" as a planet continue to stand by their research.
The IAU has not received a motion for changing Pluto's definition, but said it is good and healthy to debate.