One night about ten years ago I was walking down a quiet road on Emerald Isle, NC, the spring air spangled with stars, when a meteor flamed across the sky with such vehemence that I fully expected to hear the sound of an impact. I didn’t, of course, and on the normal scale of things, I wouldn’t be likely to. Chances are that even if the meteor did survive the fall to Earth, to become one or more of the meteorites sought by scientists as interesting chunks of the early Solar System, it landed far away and was much smaller in size than its trail seemed to imply.
Then I looked at Alan Dyer’s post on the recent meteor in Alberta, one that Dyer has illustrated with videos of the event. Taken from this week’s Carnival of Space, Dyer’s account points out that Alberta is a fine hunting ground for meteorites, but even the flat prairie can be tricky to search when you’re dealing with a momentarily visible event, a large search area and no reports of an object falling nearby. I also wondered if the average pedestrian that night wouldn’t have instinctively ducked.
The November 20 meteor over Alberta reminds us of the still unsettled state of the Solar System, and the danger that objects larger than this one might pose. Check the replay from an RCMP officer’s dashboard camera shown below, spectacular in the bright trail cutting across the sky and the fireball that follows, and imagine what might occur with an object a hundred times as large. A small near-Earth object could be far larger than the 1-10 ton meteor seen by Albertans, which is now thought to have been about as large as a chair, or maybe a desk.
Some 600 times brighter than the full Moon, it made for quite a spectacle. No wonder the local media were swamped with calls. I also notice that One Astronomer’s Noise gives a nod to a new theory of an asteroid impact that may have occurred over 2000 years ago near present-day New York City. A team from Harvard has found carbon spherules of the sort formed by extreme pressures — usually the sign of impact ejecta — in Hudson River silt. Did a 100-meter asteroid create these materials, and the tsunami whose evidence the Harvard researchers are now studying along the New Jersey and Long Island coasts? Can a crater be located?
Every major meteor sighting like the one that lit up the Albertan skies is a chance to remind the public that a prudent policy of near-Earth object detection is essential in safeguarding our future. Along with that realization comes the knowledge that a major thrust of our space program must be to develop methods of asteroid deflection in the event a serious Earth-crosser is discovered on a collision course. Some would argue that we might not need to deploy such technology for thousands of years. True enough, and I’m a gambler by nature, but this is one bet I’m not willing to take. Let’s develop the tools and sleep better at night.
Addendum: Reports from the Associated Press now say that meteorites from this event have been found near the Battle River along the rural Alberta-Saskatchewan border. And here’s a story from the Whitecourt Star on a much older crater that has now been identified in Alberta.