Pluto, which our species is seeing up close for the first time this week, is a planet almost as firmly embedded in popular culture as Mars, and yet we know comparatively nothing about it. Since it was discovered in 1930 (its presence had been predicted two decades previously), it “grew up” in the full glare of modern media, and pop culture, unlike the other planets that had been known for some time. Walt Disney may (or may not) have named his famous dog character after it, but the link was established in the minds of children all over the world for generations. That, combined with the relative lack of knowledge of the planet itself and the many odd things about it, made it something quite precious to the public imagination. Now, that photographic speck is moving from being an abstract idea to a real place, with geography and geology and living dynamics.

Pluto, when compared to the eight planets of the solar system, is very weird. It orbit is not on the plane of the ecliptic, sort of an imaginary gravitational “plate” spinning around the Sun like an LP record, but tilted and off-set, as if the turntable itself was tilted on an angle and the hole in the middle of the record was closer to one side than the other. In some of its orbit, Pluto is the farthest “planet” from the Sun, and in other parts it slips inside the orbit of Neptune (visited by Voyager 2 back in 1989), so it’s not even the “farthest planet from the Sun”.

In fact, one of the great debates over Pluto, in scientific circles, is how to categorize it. It’s so much smaller than the outer planets, for one thing, and its orbit is so strange. Furthermore, there are larger, similar objects in the neigborhood: if we’re going by size alone, than Eris and several others are also “planets” in what’s known as the Kuiper Belt. It also hasn’t “cleared the area” of other similar objects as the other planets have: it’s a long way between Jupiter and Saturn, for example, and you don’t pass anything in between. In the neighborhood of Pluto and Eris there are all kinds of other smaller objects. So, around a decade ago, astronomers opened the can of worms and “demoted” Pluto’s status to “planetoid” or “dwarf planet” or even “plutoid” object, a healthy and reasonable scientific debate. What the scientists didn’t understand or were fully aware of is that Pluto is the popular culture planet.

There’s something about this tenacious little object that doesn’t play by “the rules” of the rest of the planets that seems to really appeal. The fact that it’s so small so far away made planetary scientists appear “mean” or to be picking on this defenseless little object. The public outcry over Pluto’s reclassification took many scientists completely by surprise, and the debate continues to this day. The scientists behind the New Horizons mission, for example, which had its closest approach to Pluto this morning, call it a planet without any hesitation. Whether they defend that classification on scientific or PR grounds sort of bleeds together at this point. The lesson was learned. If the public thinks of Pluto as a planet, and not Eris (which is actually bigger…), then Pluto is a planet. Perception becomes reality.

Another reason why Pluto is the pop culture planet is that, for so long, so little was known about it. That left an open door through which science fiction and fantasy authors could race through, adding their own conceptions of what could possibly be going on, way out in that extreme and very alien environment that still obeys the laws of physics. One of the things that visiting all the planets of the solar system has shown is us the great diversity of systems that can be constructed using the same basic materials and following the same physical laws. Even on Pluto, water freezes at zero Celsius, for example. And two plus two equals four. The laws of thermodynamics are universal and inviolable, as are the laws of physical motion (otherwise, how could NASA have delivered this object so precisely from so far away). So, it’s an alien world, but it’s alien only in its application of known principles. Carl Sagan once wrote about his impatience with science fiction violating the laws of physics whenever it suited the genre, citing a story he once read about a species with a “fourth primary color”. “I spent days and days trying to imagine what a fourth primary color would look like,” Sagan later wrote, “And it always kept seeming like some shade of brown.” Some things are just too far out there.

And finally, Pluto is the pop culture planet because of the way it was introduced to the world (it was discovered using photography) and popularized, right up until today, when NASA released the first close-up images over Social Media, rather than lining up a bunch of suits at a press conference flanked by the American flag.

Pluto, from New Horizons, July 13, 2015

Pluto is different. It always has been. But now, the miracle is that Pluto is a place, not just a speck of light. It’s a place, a place you can visit. Granted, with a little more difficulty than visiting San Diego (although probably easier to get a hotel reservation), but a place nonetheless. It’s one of the last chunks of data from the humanity’s first look at our cosmic neighborhood, and while Pluto might be the red-headed stepchild of the group (it actually is slightly orange-red), that makes it both endearing and precious.