Pluto, that distant heavenly body, is on every Earthling's lips this week, thanks to new pictures sent by the New Horizons spacecraft. And with those images, and old wound has been opened: The demoting of Pluto from "planet" to "dwarf planet" status in 2006.
Plenty of folks still count Pluto as a planet. And they have their reasons. For starters, New Horizons has confirmed that Pluto has mountains and water. The International Astronomical Union doesn't consider such traits when deciding what makes a planet ... but, given that a certain third rock from the sun also has mountains and water, maybe it should reconsider.
Here are even more reasons to count Pluto among the Big Nine ...
To be a planet, a body needs to meet certain requirements, according to the International Astronomical Union.
Pluto orbits around the sun: check. Pluto has a round shape: check. But it hasn’t cleared its orbit of debris. Strike! Wait a minute, though: According to scientists, Jupiter and Earth technically violate rule No. 3 as well. And because Pluto is furthest from the sun, and dwells in a rotten neighborhood filled of debris, it gets the worst deal of them all. So cut Pluto some slack, International Astronomical Union!
Pluto has its own moon, known as Charon, and it’s geologically active, meaning its filled with things our planet is filled with, including rocks and ice. Again, the IAU cares nothing for such definitions, but its definition is extremely narrow.
The word "planet" had a broader usage for a millennia before a group of astronomers narrowed down its meaning.
Out of around 10,000 internationally registered members of the Astronomical Union, only 237 members voted to reclassify Pluto as a “dwarf planet,” while 157 voted against the demoting in the General Assembly in Prague. The other 9,500-plus members weren’t even there!
The New Horizons mission will be the first to truly explore Pluto, whereas the other planets within our solar system have already been heavily researched. We still don’t know how Pluto formed, what its atmosphere is made of, if it has a magnetic field, or a subsurface ocean. How can you classify a heavenly body you don't really know?
If Charles Bolden, head of the American space agency, can still call Pluto a planet, so can you. “It's a big day for NASA,” Bolden said recently. “The U.S. today has become the first nation to visit every planet. We're calling Pluto a planet; technically it's a dwarf planet. I call it a planet, but I'm not the rule maker."
Not yet, anyway.