Fireball Over Sweden
Last night (January 17) a fireball lit up the skies over Malmö, Sweden and was seen by people in Germany and the Netherlands. You can see a security camera view of the event here. It looks pretty spectacular and no doubt anybody who saw it was probably quite surprised and shocked.
Now the object at the heart of this fireball was probably a chunk of rock that broke up and scattered its pieces to the ground as it blasted through our atmosphere. There aren’t (yet) any reports of damage, and I imagine meteorite hunters will be swarming around suspected impact sites to gather evidence.
Stuff coming in from space is a pretty common occurrence on our planet. Most of it is dust-particle-sized or maybe the size of peas, and those pieces tend to burn up high above the surface and leave behind glowing trails. That’s usually what we see during a meteor storm.
Speaking in general terms, larger stuff (rock-sized and a bit larger) creates bolides, like the one that flared over Sweden last night. Most of the time these just break up and scatter out, leaving behind lots of cool smaller rocks for meteorite hunters to collect.
The largest material is what scientists worry about — those are typically tens of meters across and larger. That’s not what Swedes and others saw last night. I’m taking about things the size of houses or small mountains can do some real damage to Earth’s surface, including gouging out craters and slamming into populated areas. In the worst-case scenarios — like impacts of objects at least 1 kilometer across and larger — those actions could disrupt the atmosphere and perturb our global climate. One of these large impactors could create so much damage that global temperatures could plunge, leading to crop damage and destruction, and societal breakdowns. According to the folks at NASA’s Ames Research Center Impact group (led by astronomer David Morrison), studies have been done that suggest that the minimum mass of an impacting body that would produce global consequences is several tens of billions of tons. An object with that much mass would set off a groundburst explosion with enough energy to equal a million megatons of TNT. The only thing worse than that would be nuclear war (unless we had several hits of that size).
Compared to that, last night’s bolide is a mere “plinker”.