A massive object is hurtling toward me. It’s not Nature Boy racing to get the last of the pumpkin pie from the fridge.
No, the massive object in question is a giant snowball whizzing through space toward the sun. With its tail as big as a kite, Comet ISON provides the exclamation point on a year filled with objects appearing out of the great black yonder.
If the comet gods smile, we in Victoria will be able to track its progress there and back.
The comet has been touted — with qualifications — as the celestial event of 2013. Bigger than Comet PANSTARRS, which fizzled after it skirted the sun in April. Bigger in size, if not effect, than the Feb. 15 meteor that made the news over Russia. Bigger than the other meteor that passed just 27,700 kilometres from Earth that same day. Bigger even than the 2.7-kilometre-wide asteroid that whipped by, a moon in tow, this spring.
“Comet ISON,” predict skywatchers immediately prior to listing their many disclaimers, “could be the most spectacular comet to grace Earth’s skies since the Great Comet of 1680.”
In case you missed it, that comet earned its initial caps by, among other things, causing terror and panic among the residents of Manhattan Island. Given how New Yorkers have since proven to be paragons of steadiness in the face of disaster, the long-ago reaction indicates the magnitude of the Great Comet of 1680.
Isaac Newton, the English physicist and mathematician, used the same comet to formulate the laws of gravity and motion that scientists use today. (And to think, for all this time, I assumed his genius stemmed from observing apples.)
Like that renowned celestial predecessor, Comet ISON has an intimate date with the sun. About the time our neighbours to the south serve up pumpkin pie on Nov. 28, the comet will penetrate the sun’s outer atmosphere on one of the closest passes witnessed by modern scientists. At its closest approach, Comet ISON will skim within 1.2 million kilometres of the sun’s surface.
What happens next is anybody’s guess. Oh, our Thanksgiving-celebrating neighbours will pass around coffee, but this is when Comet ISON’s exclamation-point tail becomes a metaphorical question mark. The uncertainty underlies scientists’ cautious comet commentary.
The comet is a 5,000-kilometre-diameter snowman. As shopping-mall musak reminds us, Frosty fares poorly when he encounters the sun. Comet ISON’s scheduled rendezvous imperils its existence.
It also raises the stakes.
On the one hand, comets brighten as they near the sun. The sun’s heat melts the ice within the comet, releasing gases and dust that form a gloriously long tail that catches and reflects sunlight. If skies are clear before sunrise and after sunset during the next few weeks, we might — might — be able to admire Comet ISON and its tail on its final approach to our star. If the comet survives the encounter, the show might — again, might — continue into 2014.
On the other hand, the comet might — another might — be swallowed up or ripped apart by the sun. Those events would demonstrate the laws of gravity Newton used the 1680 comet to describe.
Or the comet might just fade away. While this would be anticlimactic for most Earthlings, researchers would still uncover welcome information. Already, they have gleaned evidence from the comet about our outer solar system. If Comet ISON survives its journey past the sun for just a few days, it would provide a heaven-sent window into the workings of the sun’s atmosphere.
The solar storms that light up our polar skies with aurora and threaten to disrupt our communications networks and electrical systems here on Earth originate in the sun’s atmosphere. By better understanding how it works, scientists hope to better predict those storms and better protect our satellites and power grids.
Whatever else, I predict with some certainty Nature Boy will be racing outside to watch the early morning and evening skies this month.
He may be eating pumpkin pie, too.