Are there eight planets or nine?
In the critically acclaimed Adult Swim animated comedy series Rick and Morty, Morty and his father Jerry, while working on a science project, are faced with a conundrum — well, not really much of a conundrum but it does make for a good plot device — are there eight planets or nine?
To be fair to Jerry, until 2006 (which is 12 years ago!), there were nine planets in the solar system; and there was way too much politics on Pluto for Jerry to have come to a coherent conclusion. In 2006, however, some scientists decided they liked their numbers even and demoted poor Pluto, the last guy in the line, to a “dwarf planet”.
Well okay, that wasn’t really the reason they did that.
The International Astronomical Union (IAU) actually came to this conclusion because of the discoveries of Kuiper Belt Objects (KBOs) — a population of small, icy bodies beyond the orbit of Neptune — with masses roughly comparable to that of Pluto.
There were only two ways to go about it. Either expand the list of planets from nine to 12, or demote Pluto; although Professor Owen Gingerich, who chaired the IAU planet definition committee, said, "In a sense we're demoting Pluto by taking it off the list of classical planets. But we're promoting it by making it the prototype of this new category of Plutons". The first idea was a highly radical one, and one with many flaws.
The other option — demoting Pluto — was the more rational one, considering Pluto did not meet one of the three criteria that defined the status of a planet: (1) It is in orbit around the Sun. (2) It has sufficient mass to assume hydrostatic equilibrium (a nearly round shape). (3) It has "cleared the neighbourhood" around its orbit. Pluto, sadly (for those who still find this demotion unfair) met only the first two categories. It got shifted into a new category — and some would say it was almost akin to making a new designation for those employees you don’t want to have but can’t fire (pretty sure those people who believe that are not scientists at all) — Trans Neptunian Objects (TNOs).
But enough about the sorry tale of the dwarf whose name sake is the Roman God of the underworld.
It is a bit of a good sob story, but mostly, it’s a tangential arc in the main story.
Why? Because with or without Pluto, the question that still remains relevant today is: are there eight planets or nine?
The answer just may be the latter.
But if not Pluto, then who (or rather, what)?
Well, first of all, scientists have long believed that there exists a ninth planetary body beyond the Kuiper Belt. Their belief is that this guy does not like the attention (and thus hangs out really far away, like the backbenchers), is a bit of an enigma, and it’s one cold sod (to be fair, he is pretty far away from any real warmth). But, the problem is that the evidence of such a planet, so far, has been quite circumstantial.
Konstantin Batygin and Mike Brown, two planetary astrophysicists with the California Institute of Technology (Caltech), theorised the existence of this heavenly body in 2016. Affectionately called “2015 BP519”, this was described by Batygin and Brown as a “missing super-Earth”. It’s not any kind of (heavenly) body-shaming, because this mystery planet is believed to weigh somewhere between five and 20 times the mass of Earth. But what made this supposed bad boy (or girl) interesting is how it stands: Its orbit is tilted 54 degrees with respect to the plane of the solar system.
According to some reports, “2015 BP519” has quite the gravity field and its milkshake is bringing all the TNOs to its yard.
But, not everyone has the kind of faith Batygin and Brown exude.
According to a report in June published by The Inquisitr, a new study was presented at the 232nd meeting of the American Astronomical Society, where Ann-Marie Madigan, an assistant professor in the Department of Astrophysical and Planetary Sciences at the University of Colorado Boulder, and her colleagues argued that it was collective gravity of many, many bodies in the Kuiper Belt, and not some “enigmatic unseen planet”, that messed around with orbits.
Are the naysayers wrong? Who knows! No one has seen anything so far back. Like one memorable episode from Dexter’s Lab where Dexter loses his lucky pencil to the back of the bus and no one could see at the back of the bus because of how dark it was, the area post the Kuiper Belt is pretty dark. And it makes sense. According to a Washington Post report, being that far away — up to 1,000 times farther from the sun than Earth — makes it “essentially invisible to our observatories.”
To make that math clearer, a Quanta Magazine report patiently explains that if this ninth guy was located 600 times farther away from the sun than Earth, or about 93 million miles, it would look 160,000 times dimmer than Neptune. Another factor worth considering is that the wavelength of light supposedly coming from this maybe-planet, which scientists anticipate shines in the millimetre part of the spectrum, which is between infrared light and microwaves.
At one point, it almost feels like the planet just does not want to be seen by humans. There are too many things that can keep it hidden. The planet could be hidden by the glare of a bright star or the light pollution in the Milky Way. Or the planet, travelling in an elliptical orbit, could easily move to a more distant point, basically beyond the 1,000 Astronomical Unit (AU)-limit, making it entirely invisible for at least a thousand years.
So many things that can go wrong; it is possible the ninth planet may never be known to anyone in this lifetime (oh, the tragedy). But that still doesn’t mean it’s not there. Mostly, one can always hope. Believe in their heart, like Jerry Smith from Rick and Morty, that no matter what big-wig scientists say, there are nine planets!