Northwest skywatchers have had their hands full this morning, with the passing of Asteroid DA14, and a spate of meteor strikes last night in Russia.
Professor Greg Bothun of the University of Oregon's Physics Department says, "This kind of event probably occurs once every 100 years, certainly not once every 10 years, or once every 1000 years."
A very hard meteoroid, something with high density, made of solid rock, he says, would have hit the ground. "This event looks to be a lower density meteoroid, likely with an ice/rock mixture, which fragments more easily."
Bothun points out the meteor appears to have entered the atmosphere was a very shallow angle. This allows the object to spend more time in the atmosphere which then facilitates fragmentation and disintegration as a fireball in the atmosphere. He says it also tells us something about how big the object was. "In order to survive that path length through the atmosphere the original object had to be on order of 10-20 meters in diameter. It's impossible for our current technology to detect something of that relatively small size, so that's why no advanced warning could be given."
Jim Todd runs the Planetarium at Oregon Museum of Science and Industry. He says the minute he saw the videos of giant fireballs streaking across the Russian sky, he knew what was going on. He calls it the largest bolide, as astronomers call them, ever captured on video. Todd says there's no reason to think the Russian incident and Asteroid DA14 are related.
Jim Todd "DA14's path is going from the south to the north, in relation to the earth. The fireball that happened last night was emerging from the east to the south. They're two totally different paths."
Oregon and Washington didn't get a very good view of DA14's fly-by. It was closest to earth's other side. But Todd says he's looking forward to photos and data NASA is collecting. He says they'll provide a better sense of the asteroid's passage through space.