originally published November 26, 2013
If you haven’t read the article or seen the t-shirt, you’re probably nevertheless aware that our ninth planet, Pluto, was demoted in 2006 to the meager status of dwarf planet, a lower classification that for whatever reason enraged pockets of the populace. I suspect a chunk of that outrage had to do with one of our ingrained snippets of knowledge – the names of our solar system’s planets – that we remember from elementary school being altered. It’s fundamental, like the names of our Canadian provinces (which has changed) or the five senses (though actually there are several others).
But amid all this weird hype over a remote ice-rock and whether it still gets invited to the same imaginary shindigs as Saturn or Venus, we forgot to celebrate little Ceres. Ceres was also tossed into the dwarf planet class along with Pluto and three others, but for Ceres it was a promotion. Where once she was just a passenger amid the rush-hour gridlock of the asteroid belt, now she reigned supreme.
And as much as we all have Pluto’s name etched in our brains as the last fuelling post before the great black expanse of deep space, we know almost nothing about Ceres. And her secrets might be among the most interesting in our little corner of the cosmos.
Much like the grainy footage of Bigfoot, this is all we’ve got of Ceres: a blur, courtesy of the Hubble Telescope. We know surprisingly little about this chunk of rock, though NASA is aiming to change that when the Dawn spacecraft pays Ceres a visit early in 2015. Ceres was discovered due to math, which means that I’ll be covering this portion of the story using the most vague and non-researched terms possible.
In 1800 the world’s leading astronomers were charting out the planetary orbits of the known population of our solar system, which at that time went as far as Saturn. But something was missing – there had to be something twirling around the sun between Mars and Jupiter, because math told them so. A team of 24 aces in the field met up in Lilienthal, Germany, and formed the United Astronomical Society, known among industry insiders as (and I’m not making this up) the ‘Celestial Police’.
A few months later it was an Italian astronomer named Giuseppe Piazzi, not a member of the Star-Cops, who found Ceres. He thought it was a comet at first, but closer examination (he squinted) revealed it to be a planet. A few months later another object was found, except that these doohickeys were moving too fast to be observed clearly like the other planets. They looked like stars, despite being clearly located on the near side of Jupiter’s orbit. William Herschel was the guy who suggested they be given a new designation: asteroids, meaning ‘star-like’.
Brilliant. Except that it took several decades for that term to catch on, and Ceres and Pallas (the other asteroid) were simply known as planets for a while. Napoleon’s army burned down the observatory at Lilienthal, which set back our learning a little, but by 1845 they had pinpointed five objects in what we now call the asteroid belt. Ceres had plenty of company, but she still found ways to stand out from the crowd.
Ceres may be a tiny chunk of rock when compared with the planetary slabs in our solar system, but she takes up roughly a third of the mass of the entire asteroid belt, or about 4% of the mass of our moon. If you can imagine the surface area of India or Argentina folded into a sphere, then you’ve got an idea of Ceres’ girth. Her innards are made up of rock, but she’s coated by an icy mantle layer which contains about 200 million cubic kilometers of water. That’s more than Earth’s supply of fresh water.
So if that’s true – if there’s that much ice crammed onto this little planetoid, it’s also possible that there could be life squirming about. That’s a huge if that’s relying on another huge if. We don’t know for certain that Ceres is boasting a big ice shell beneath her blurry visage; we simply lack the data. For now.
This is a dramatic, whooshing rendering of NASA’s Dawn spacecraft, launched on September 27, 2007 and destined to be the first spacecraft to orbit two extraterrestrial bodies. Dawn swooped by Vesta, also a resident of the asteroid belt and the brightest member of that community from Earth’s perspective. Dawn entered her orbit – yes, I know that sounds dirty – on July 16, 2011, and mapped the crap out of the thing. A couple months later it was on its way to Ceres.
It’s expected Dawn will arrive to snap some close-up pics of Ceres in February of 2015, at which point we should acquire a much firmer grasp on what Ceres is and how she was formed. No one is expecting we’ll come across alien life waving up from the surface, but hopefully we’ll be able to tell if there’s any down there.
And maybe someone will figure out what the hell that white dot is all about.
In 1995 Hubble caught a few snapshots of dark spots on Ceres’ surface, believed to be craters. The Keck telescope (plopped atop a dormant Hawaiian volcano) also noticed that one of these so-called craters has a bright spot at the heart of it. No one knows that that bright spot is. Another mystery that will hopefully get blasted apart when Dawn comes a-knockin’.
So in 2006 when astronomers planted the big rubber stamp on what is considered a true planet, people bemoaned Pluto’s reclassification as a dwarf. But Ceres entered the discussion here: she has enough mass to create her own gravity, and she is in orbit around a star and not another planet. The only criteria she doesn’t meet to become a planet is that she is not in command of her own orbit – she shares it with a roughly a zillion other asteroids. This is the same loophole that bumped Pluto off the planet leaderboard.
This leaves us with five dwarf planets: Eris (the big one), Pluto (the forsaken one), Haumea (the quiet one), Makemake (the one named after an Easter Island god of a bird-man cult) and Ceres. Ceres is the only dwarf planet that isn’t on the solar system’s periphery, hosting the bustling fiesta just past Mars. She may not be a full-fledged planet, but I think she deserves a little love.
Especially if she can show us a bit of sentient company out in cold space.
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