TAURID FIREBALLS: Sky watchers should be alert for fireballs in the nights ahead. Forecasters say Earth might be heading for a swarm of gravelly debris from comet Encke. If so, meteoroids the size of pebbles and small stones hitting Earth’s atmosphere at 25 km/s would produce a slow drizzle of very bright fireballs flying out of the constellation Taurus–hence the name “Taurids.” The display is expected to peak with a few fireballs every hour during the nights of Nov. 5-12.
NASA’s network of all-sky meteor cameras is already picking up some Taurid fireballs–“7 in the past two nights and 11 altogether since Halloween,” reports Bill Cooke of the Meteoroid Environment Office. Here are their orbits:
In the orbital diagram, the location of Earth is denoted by a red splat. The orbits of the meteoroids (yellow) roughly match that of parent Comet Encke (orange), confirming their association with the Taurid debris swarm.
“What always strikes me about the Taurids,” notes Cooke, “is how deeply they penetrate Earth’s atmosphere. On average, they make it to an altitude of 44 miles. Contrast this to the recent Orionids, which burn up at an average altitude of 58 miles. Part of this is due to the speed difference: Taurids are slow (27 km/s) while Orionids are fast (66 km/s). In addition, many Taurids are made up of stronger stuff than the Orionids.”
Yesterday, Cooke received this report from a hunter in Tennessee, who was near the terminus of a Taurid fireball which made it all the way down to 18.5 miles altitude: “On the morning of October 30 at approximately 6:00 CDT I was walking into a hunting spot in the middle of the Hatchie National Wildlife Refuge. As I was standing, this bright white light appeared from the north, illuminating the woods like daylight, casting shadows of the trees, and as it passed overhead in a couple of seconds, the shadows quickly reversed direction. It was so intense I felt like a searchlight from an overhead helicopter was on me, but there was no noise. As it disappeared into the southern sky, I heard three extremely loud booms which I also felt much like a sonic boom from a plane. The resident birds all began to call for a minute after. In my 62 years of living on this planet, and witnessing several meteor showers- some very bright- I can tell you I have never witnessed anything like this. The experience was not totally unlike that seen in the movie Close Encounters of the Third Kind when the man’s truck was stopped at a railroad crossing and he was engulfed in light!”