So what’s big, rocky, round and sits between Mars and Jupiter? If you’re scratching your head right now, don’t worry. Your 7th grade science teacher didn’t teach you about it because it wasn’t deemed worthy, but there is something out there.
On January 1, 1801, the Mathematician, Astronomer, and Catholic priest of the Theatine order, Father Giuseppe Piazzi, made a startling discovery. An object first thought to be a star (one of 7,646 that he cataloged in his career) was observed moving against a field of its fixed cosmic kin. To verify his findings Piazzi spent 3 more days making observations. What had he found? Well according to him it must have been a comet – a large ball of dust and ice, traveling through the solar system like a cosmic drifter. Only that’s what he felt comfortable telling the public. His instincts told a different story, as we can tell from a letter sent to his friend, Barnaba Oriani:
“I have announced this star as a comet, but since it is not accompanied by any nebulosity and, further, since its movement is so slow and rather uniform, it has occurred to me several times that it might be something better than a comet. But I have been careful not to advance this supposition to the public.”
He named it “Ceres Ferdinandea” after the Roman god of grain and King Ferdinand IV of Naples. Later the object in question would have its name shortened to just Ceres. So what’s “better than a comet”? Why a planet, naturally. Then why didn’t Father Piazzi just come out and say it? For one, Ceres was about to move into the glare of the Sun making it impossible to observe further, and sadly the mathematics of the time made it impossible to predict when it was going to reappear. That was until the young genius Carl Friedrich Gauss introduced a new method of orbital calculation that allowed this elusive “comet” to be discovered once more.
It then begs the question, with such a touching tale of love lost and found once more, why have you never heard Ceres mentioned among the honored members of the solar system? It didn’t just disappear (ok it did… but we found it, remember?) There was once a time when Ceres and other similar objects were in text books as planets, jumping back and fourth between this distinction and that of asteroid for many years. However, as more powerful telescopes came into existence, it became more and more clear that these bodies were not nearly as impressive in size, and thus not worthy of the distinction of planet. Sadly for little Ceres, size did matter. That was until Pluto was found.
In 1930, Pluto was discovered, the world was delighted to have a ninth planet to call our own. Yet in the 1970’s, it was revealed that Pluto’s mass was only 1/3 that of Earth’s moon – much smaller than previously expected. This made us question what it really was to be a planet. In 2006, the IAU (International Astronomical Union) decided to take on this question and determined the following:
The IAU therefore resolves that planets and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way:
(1) A “planet” is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
(2) A “dwarf planet” is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects, except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”.
Poor little Pluto…simply because it has smaller neighbors in close orbit it was no longer deemed worthy of planetary status. Over night, Pluto was gone and 7th graders everywhere were very confused and people like myself were pissed. How dare anyone tell me that this beloved little icon of modern astronomy had been “demoted”. What a way to take out the underdog; at the very least, give Pluto a respectful demise. Demoted sounds so pathetic, almost like Pluto and the other dwarf planets had done something wrong and were being punished. Yet that is exactly what has happened. In this day and age, the public has nearly forgotten about space exploration, so let’s just remove as many interesting astronomical bodies as possible from everyone’s view. That makes sense right? Now any hope of Ceres returning to the ranks was gone.
It makes me wonder who it was that benefited from this whole debacle? It certainly wasn’t dwarf planets. However, the AIU got some much needed attention. This brings me to the now famous Neil Degrasse Tyson, director of the Hayden Planetarium and public figure head for mob that killed Pluto. Don’t get me wrong, Neil is a good astronomer and fun to watch on Nova Science Now, but it makes me wonder how well he sleeps at night.
So Ceres and other dwarf planets are small and crowded. So what? I see no problem with having 13 planets rather than 8. Make Ceres a planet and while you’re at it give Pluto back its rightful place and give these two little guys some company. Dwarf planets are planets, too, and giving more public attention to our local solar system can’t hurt. Pluto’s discovery caused so much excitement that a town in the United States renamed itself in Pluto’s honor. Just think of the excitement adding several new planets would do too bolster a terribly depleted enthusiasm for the American space agency. Perhaps in 2015, when two separate probes (New Horizons headed to Pluto and Dawn headed for Ceres) will reach their destination and give us our first of close looks at Pluto and Ceres, it will change something. Maybe when we have a look at our victims, the attitude of the AIU might be more open minded. If it doesn’t, then maybe you should speak up in defiance, I know I will. Next time some asks you, “How many planets are there in the solar system?,” say, “13”.