My very educated mother just served us nine pizzas—that was the mnemonic this mere Trivia Geek learned to remember the names of the nine planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.
A couple decades past the third grade, that little memory aid is in desperate need of a rewrite, as the International Astronomical Union has finally issued a ruling on what constitutes a planet and what doesn't. Pack your bags, Pluto, because now we've got ourselves an eight-planet solar system.
For those who weren't aware that the definition of a planet was up for debate, blame Pluto. That eccentrically-orbiting ice ball has almost nothing in common with the other eight traditionally recognized planets, so astronomers have long debated reclassifying Pluto as a non-planet.
Some folks, however, couldn't stand the notion of demoting one of the "classical" planets, and the IAU briefly considered instituting a broader definition of planethood that would have included Pluto—and at least three other major objects in our solar system. One way or another, somebody's educated mom was going to be serving something other than nine pizzas.
Here's the rundown of the three newly anointed planets under this now-discarded standard: Ceres (the largest rock in the asteroid belt), 2003 UB313 (the largest trans-Neptunian object in the solar system), and Charon (Pluto's largest moon). (Pluto has two other moons, Hydra and Nix—both discovered in 2005.)
Yes, you read that right—science almost elevated the object once thought to be Pluto's moon to planethood itself under this IAU draft proposal. It turns out that Pluto and Charon are a binary pair of objects that orbit around each other, rather than a typical planet-moon relationship. This may explain why the IAU didn't adopt the Pluto-inclusive draft—and why Pluto got the boot.
Despite the radical departure from the accepted planetary lineup, the three proposed "new" planets weren't entirely unprecedented in their selection. At least one member of the trio had achieved planet status in the past—only to later lose it in much the same fashion as Pluto.
WHICH OF THE THREE "NEW" PLANETS CONSIDERED IN A RECENT IAU RESOLUTION WAS A RECOGNIZED PLANET IN THE 1800s?
Which of the three celestial objects nearly elevated to planethood by the IAU in the summer of 2006 was a recognized planet in the 1800s?
This one was a bit of a gimme, since we didn't even know about 2003 UB313 until 2005 (from pictures taken in 2003), and astronomers discovered Charon in 1978. Yes, asteroid Ceres' original classification was a planet almost immediately after its discovery in 1801—although its ambiguous planetary status would lead indirectly to the concept of asteroids.
When astronomer Guiseppe Piazzi first detected Ceres on Jan. 1, 1801, he thought it was a comet. However, Piazzi's discovery moved rather slowly across the sky, suggesting that his original comet classification might be incorrect.
In the same era, astronomers Johann Elbert Bode and Johann Daniel Titius were searching frantically for a "missing" planet that their calculations showed had to exist between the orbits of Mars and Jupiter (a common theme in the history of astronomy). This popular search led to the anointment of Ceres as a formal planet—along with three other nearby objects: Pallas, Juno, and Vesta.
Alas, this quartet of "planets" turned out to be significantly smaller than the previously noted local orbs, and astronomers found themselves in much the same situation as modern star watchers did with Pluto—they had planets that didn't really seem to live up to their billing.
It took the intervention of the legendary Sir William Herschel—he who discovered both infrared radiation and the planet Uranus—to settle the issue. He coined the term asteroid in 1802—just after the discovery of Ceres and Pallas—to describe star-like objects that weren't planets or comets.
After 50 years of uncomfortable planethood, astronomers demoted Ceres and its diminutive sisters to asteroids, and the search for other members of the asteroid belt has continued ever since. Today, there are hundreds of thousands of asteroids catalogued by astronomers—with about 5,000 added every month.
Still, of the asteroids found in the main asteroid belt, Ceres is still the top dog, accounting for nearly one-third of the belt's total mass. That's not just a big rock—it's also some heavy Geek Trivia.
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The Quibble of the Week
If you uncover a questionable fact or debatable aspect of this week's Geek Trivia, just post it in the discussion area of the article. Every week, yours truly will choose the best post from the assembled masses and discuss it in the next edition of Geek Trivia.
This week's quibble comes from the September 6 edition of Geek Trivia, "Planet X marks the spot." TechRepublic member RealGem smacked me for a mythological misstep when I suggested that all of our local planets derive their names from Roman gods.
"Uranus is actually Greek, representing the sky. And, he wasn't technically a god. He fathered the Titans, who fathered the gods, so technically he was Zeus' grandpa. His Roman equivalent was Caelus, also the god of the sky—and probably where we get the word ceiling from. So, Uranus is the only planet not named after a Roman god."
You learn something every day. Thanks for the Greco-Roman clarification, and keep those quibbles coming.
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The Trivia Geek, also known as Jay Garmon, is a former advertising copywriter and Web developer who's duped TechRepublic into underwriting his affinity for movies, sci-fi, comic books, technology, and all things geekish or subcultural.
Jay Garmon has a vast and terrifying knowledge of all things obscure, obtuse, and irrelevant. One day, he hopes to write science fiction, but for now he'll settle for something stranger — amusing and abusing IT pros. Read his full profile. You can also follow him on his personal blog.