A tale of two space rocks
Two space rocks flew through our part of space this week. One blew up over Montreal, the other had a tug of war with the sun. We compare them, head to head.
COMET ISON
❚ First appeared far out in the solar system in 2012, where a Russian astronomy group with the initials ISON recognized it as a comet.
People threw around phrases like “comet of the century,” because there was a chance that this newcomer, passing close to the sun, would be heated and release a huge “tail” of gases from its frozen centre.
❚ It went behind the sun Thursday, and at first astronomers thought it had been destroyed by the sun’s heat and gravity.
Then a speck appeared, coming out the other side. But there isn’t much left. Here’s NASA’s astronomy website: “The question remains whether it is merely debris from the comet, or if some portion of the comet’s nucleus survived, but ... analysis from scientists with NASA’s Comet ISON Observing Campaign suggest that there is at least a small nucleus intact.”
The original forecast was that a comet might be visible to the naked eye by the first days of December. All bets are now off.
❚ ISON’s original size was estimated at a little less than five kilometres wide, made of rock, dust and frozen gases. In effect, it may have gone from the size of Orléans to the size of Place d’Orléans.
It approached to within 1.2 million kilometres of the sun’s surface, and astronomers call comets like this “sungrazers.”
MONTREAL METEOR
❚ Appeared and then disappeared seconds later with a blue flash of light and a bang just before 8 p.m. Tuesday, in heavy cloud.
❚ No one has found pieces, but astronomer Peter Brown of Western University announced that it does appear to be a meteor.
“The ballistic shock and some likely fragmentation events were detected by the infrasonic micro- phones attached to various stations of the USArray,” he reported. He says the fireball went roughly north to south “passing almost right over the Island of Montreal. Stations to the South show three distinct arrivals which may indicate a series of fragmentation episodes near the terminal part of the path.”
He calls the shock that created the loud noise “very small,” and estimates the rock’s original size “in the tens of kilos category.” Only a small portion of a meteor generally survives as fragments that reach Earth.