Having seen some footage of the South African fireball last weekend, I thought it was quite impressive. However, a new video looking along a Johannesburg motorway has appeared online, and it’s superb.
I can’t find much information about this event, but it happened on November 21st and no fragments have been found so far.
Just in case you were in any doubt as to how much energy is released when a chunk of rock hits our atmosphere, this should give you a good impression:
I could almost feel the heat and hear the *KABLAAAM*.
Bolide breakup and impact on the surface of Mars (HiRISE/NASA)
Earth has been hit numerous times in recent months by some large chunks of space rock. One of the larger meteoroids to enter the atmosphere was the November fireball over Saskatchewan, Canada. In this case, an estimated 10 tonne meteorite slammed into the atmosphere, creating a bright bolide (fireball), exploding into fragments. Fortunately, eyewitnesses were able to pinpoint the location of possible debris. Sure enough, after an extensive search in the rural area of Canada, meteorite fragments were found.
However, these fragments did not impact the ground at the hyper-velocities that the original fireball was travelling at, the Earth’s thick atmosphere created an efficient barrier, through air resistance, breaking up the bolide. In this case, an energetic explosion was observed for miles around. Fragments from the fireball then fell at a maximum speed of terminal velocity, bouncing off the ground. Some fragments sat proudly on top of frozen ponds – the debris final kinetic energy was so low that little damage would have been done even if the small rocks scattered over a populated area (unless, of course, someone got hit on the head – they would have had a very bad day).
OK, so we’re well protected from most bits of junk space can throw at us. Most meteoroids, from the size of a grain of sand to the size of a small bus, will burn-up, break-up or explode high in the atmosphere, scattering bits on the ground. But what about Mars? What if Mars gets hit by a sufficiently-sized meteoroid?
Even if the meteoroid does break apart, unfortunately the atmosphere is too thin to slow the debris sufficiently. A lack of air resistance makes for more impressive impact craters. Watch your heads future Mars colonists, you could be faced with a shotgun blast from space… Continue reading “Mars Gets Hit By Cosmic Buckshot”
Video of the fireball event over Colorado (Chris Peterson)
Early this morning, a huge explosion lit up the Colorado skies. According to one observatory that videoed the event with its ever-watching all-sky camera, the fireball (or bolide) peak brightness (magnitude -18) exceeded the brightness of a full Moon 100 times. An awesome event. The Cloudbait Observatory, near Denver, is calling on eye-witnesses to submit their reports so possible meteorite fragments can be found on the ground. Only last month, a similar effort resulted in Canadian meteorite hunters finding over two dozen fragments from the Saskatchewan fireball.
I must admit though (as one of my readers pointed out), it is surprising to hear about this recent flurry of large fireball events. Some of these meteoroids are as big as 10 tonnes (in the case of the Saskatchewan fireball), and scattered meteorites are being found on the ground (fortunately over sparsely populated regions). Are these recent series of fireball spottings down to improved observation techniques and a bit of luck? After all, the October fireball was observed directly over several all-sky cameras dedicated to spotting meteors; the November fireball was seen by a huge number of people in cities across the Saskatchewan/Alberta border and last night’s fireball appeared above another dedicated meteor all-sky camera.
A few of these events are expected every year, so this is certainly nothing to be concerned about, we’re just getting better at observing these transient events…
astroengine.com 