Camelopardalids meteor shower reveals comet's active past
Comet 209P/LINEAR makes closest approach Thursday
A one-off meteor shower over the weekend wasn't spectacular, but it produced some nice images and enough meteors to reveal new information about a mysterious comet.
The Camelopardalids meteor shower peaked early Saturday morning, as predicted, when the Earth passed through debris left by the comet 209P/LINEAR on previous orbits. Meteor showers take place when dust and small rocks dropped by comets hit the atmosphere and burn up, producing a bright light as they fall.
Many skywatchers on Twitter and on the Meteorobs internet forum for meteor observers expressed disappointment about Saturday's show. Most who responded to the Canadian Space Agency's Twitter query about whether the show was a "boom or bust" said they saw only a single meteor or none at all, despite some predictions that the Camelopardalids could generate up to 100 or 1,000 meteors per hour.
"Disappointment here in Alberta as well. A dozen observers combined to see zero unambiguous Camelopardalids," wrote Meteorobs member Bruce McCurdy in response to a similar disappointed post from Virginia.
"It wasn't on the high end of predictions," acknowledged Paul Wiegert, an assistant professor with Western University's Meteor Physics Group.
Nevertheless, Wiegert said, he and his colleagues likely captured hundreds of images — including many too faint to be seen by eye — with their network of meteor cameras.
'Nice and slow, distinctly yellowish'
"We did see some really nice ones," Wiegert said. "They were very nice and slow, distinctly yellowish — and you could kind of see a few of them breaking apart, some of the brighter ones — so we did have a really nice show."
He said he had seen estimates that there had been about 20 to 50 meteors per hour, with a higher number of brighter meteors than predicted.
Based on that information, "we've learned the comet was much more active in the past."
The debris that generated the meteors would have been dropped by the comet about a century ago, on previous orbits. That's because it's currently quite dim and inactive, making it hard to see even though it's coming closer to Earth than any other comet since 1983 (when IRAS-Araki-Alcock, passed within 4.5 million kilometres of Earth).
The comet will pass within eight million kilometres (about 21 times the distance between the Earth and the moon) of Earth during its closest approach this Thursday and will be at its brightest Wednesday night, but won't be visible without a telescope.
"Comets are expected to be fainter as they get older," Wiegert said. "Now we can put some definite numbers to that."
However, a lot of data still needs to be analyzed, he added.