1 00:00:02,040 --> 00:00:07,280 Speaker 1: Welcome to brain Stuff from How Stuff Works. Hi brain Stuff, 2 00:00:07,360 --> 00:00:12,160 Speaker 1: Lauren boblebam here. One November afternoon, in residents of fifteen 3 00:00:12,160 --> 00:00:15,600 Speaker 1: Alabama counties were reportedly startled by a loud boom that 4 00:00:15,720 --> 00:00:18,800 Speaker 1: caused some to call nine one one operators in alarm. 5 00:00:18,800 --> 00:00:22,279 Speaker 1: As the National Weather Services Birmingham station tweeted not quite 6 00:00:22,320 --> 00:00:25,520 Speaker 1: a couple hours later, there wasn't any clear explanation for 7 00:00:25,520 --> 00:00:28,800 Speaker 1: the noise. Radar scans and satellite imagery of the region 8 00:00:28,840 --> 00:00:31,600 Speaker 1: didn't show any large fires or smoke from an explosion, 9 00:00:31,920 --> 00:00:34,600 Speaker 1: and the U S Geological Survey didn't spot any signs 10 00:00:34,600 --> 00:00:38,000 Speaker 1: of an earthquake on its seizemic monitoring system. In their tweet, 11 00:00:38,080 --> 00:00:40,640 Speaker 1: the National Weather Service speculated that the sound may have 12 00:00:40,680 --> 00:00:43,559 Speaker 1: been caused by an aircraft or meteor, but said we 13 00:00:43,600 --> 00:00:46,239 Speaker 1: don't have an answer and we can only hypothesize with you. 14 00:00:47,320 --> 00:00:51,640 Speaker 1: A NASA scientist soon knocked down those possible explanations. Bill Cook, 15 00:00:51,760 --> 00:00:54,960 Speaker 1: head of these space agencies Meteoroid Environment office at the 16 00:00:55,080 --> 00:00:58,720 Speaker 1: Marshall Space Flight Center in Huntsville, Alabama, told al dot 17 00:00:58,760 --> 00:01:00,720 Speaker 1: com that he was skeptical that sound could have been 18 00:01:00,760 --> 00:01:03,400 Speaker 1: caused by meteor because there were no reports of anyone 19 00:01:03,440 --> 00:01:06,800 Speaker 1: seeing a fireball. Cook also discounted the possibility that the 20 00:01:06,800 --> 00:01:09,240 Speaker 1: boom had been created by an aircraft, noting that the 21 00:01:09,240 --> 00:01:13,639 Speaker 1: seismic signature is not characteristic of that produced by supersonic jets. 22 00:01:13,640 --> 00:01:17,720 Speaker 1: Boom about six hundred miles or nine and seven kilometers 23 00:01:17,760 --> 00:01:20,959 Speaker 1: to the north in Ontario, Canada, the Elgin Field infrasound 24 00:01:21,000 --> 00:01:24,119 Speaker 1: array picked up an infrasound wave that apparently was linked 25 00:01:24,160 --> 00:01:26,920 Speaker 1: to the boom. It usually takes something pretty big, such 26 00:01:26,920 --> 00:01:29,399 Speaker 1: as a severe storm and avalanche or a rocket launch 27 00:01:29,440 --> 00:01:32,319 Speaker 1: to trigger such a wave. To add to the weirdness, 28 00:01:32,480 --> 00:01:35,800 Speaker 1: less than two weeks later, another similarly unexplained boom was 29 00:01:35,880 --> 00:01:38,880 Speaker 1: heard one morning in the Birmingham area. We spoke with 30 00:01:38,959 --> 00:01:43,280 Speaker 1: James Cooker, director of the Jefferson County, Alabama Emergency Management Agency, 31 00:01:43,440 --> 00:01:46,360 Speaker 1: via email. He said that he heard a double boom, 32 00:01:46,400 --> 00:01:48,880 Speaker 1: although the sound I heard may have included an echo 33 00:01:49,000 --> 00:01:52,720 Speaker 1: caused by the mountains, he said, and Alabama isn't the 34 00:01:52,760 --> 00:01:56,280 Speaker 1: only place where things have been booming lately. Skyquakes as 35 00:01:56,280 --> 00:01:59,440 Speaker 1: they're commonly called, recently have been heard across the US 36 00:01:59,600 --> 00:02:02,440 Speaker 1: in stay ranging from New Jersey to Idaho, as well 37 00:02:02,480 --> 00:02:04,760 Speaker 1: as in places as far away as India, where two 38 00:02:04,760 --> 00:02:07,480 Speaker 1: seaside resort towns were jolted in August by a boom 39 00:02:07,520 --> 00:02:10,320 Speaker 1: so loud that it shattered hotel windows, according to the 40 00:02:10,440 --> 00:02:14,920 Speaker 1: Dacca Tribune. Indeed, as u S Geological Survey scientist emeritus 41 00:02:15,000 --> 00:02:18,640 Speaker 1: David Hill detailed in a article on the subject, mysterious 42 00:02:18,680 --> 00:02:21,240 Speaker 1: booms have been heard for many years in places across 43 00:02:21,280 --> 00:02:24,519 Speaker 1: the world. In Belgium, they're known as MIAs poofer's, while 44 00:02:24,560 --> 00:02:27,560 Speaker 1: the Italians call them bron titi. In the vicinity of 45 00:02:27,680 --> 00:02:30,520 Speaker 1: Lake Seneca and the Catskill Mountains of New York, residents 46 00:02:30,520 --> 00:02:33,360 Speaker 1: have long heard the Seneca guns, a phenomenon that was 47 00:02:33,400 --> 00:02:36,519 Speaker 1: described by author James Fenimore Cooper back in eighteen fifty 48 00:02:36,560 --> 00:02:39,720 Speaker 1: one as a sound resembling the explosion of a heavy 49 00:02:39,720 --> 00:02:42,320 Speaker 1: piece of artillery that can be accounted for by none 50 00:02:42,320 --> 00:02:45,400 Speaker 1: of the known laws of nature. As Hill noted in 51 00:02:45,480 --> 00:02:49,000 Speaker 1: his article, numerous explanations for skyquakes have been proposed over 52 00:02:49,040 --> 00:02:52,400 Speaker 1: the years, including shallow earthquakes that could produce audible sounds 53 00:02:52,400 --> 00:02:56,120 Speaker 1: without noticeable shaking, massive tsunami waves breaking far from shore, 54 00:02:56,480 --> 00:02:59,880 Speaker 1: explosions of methane gas released from the methyl hydrate beds 55 00:03:00,160 --> 00:03:04,440 Speaker 1: sand dunes, shared by avalanches and of course meteors. As 56 00:03:04,520 --> 00:03:07,880 Speaker 1: Hill wrote, meteors penetrating the upper atmosphere could create sonic 57 00:03:07,919 --> 00:03:10,720 Speaker 1: waves that wouldn't reach Earth's surface until after the meteor 58 00:03:10,760 --> 00:03:13,720 Speaker 1: had vanished, so the connection between the two wouldn't be apparent. 59 00:03:14,680 --> 00:03:17,440 Speaker 1: People have also raised the possibility that the booms, or 60 00:03:17,480 --> 00:03:19,880 Speaker 1: at least some of them, might be caused by tests 61 00:03:19,880 --> 00:03:22,760 Speaker 1: a secret U S military aircraft, such as the long 62 00:03:22,840 --> 00:03:26,680 Speaker 1: rumored spy plane that aircraft buffs have dubbed Aurora. However, 63 00:03:26,840 --> 00:03:29,960 Speaker 1: there may not be one single explanation for all the booms. 64 00:03:30,520 --> 00:03:33,280 Speaker 1: Hill explains it is indeed the case that there may 65 00:03:33,320 --> 00:03:36,520 Speaker 1: be several plausible explanations for any given incidents of a 66 00:03:36,560 --> 00:03:39,440 Speaker 1: mysterious booming sound, and that the environment where the sound 67 00:03:39,480 --> 00:03:42,200 Speaker 1: is heard will determine which of the possible explanations are 68 00:03:42,200 --> 00:03:44,560 Speaker 1: the most reasonable. A sound heard in the middle of 69 00:03:44,600 --> 00:03:47,600 Speaker 1: the desert, for example, is not likely due to breaking surf. 70 00:03:48,520 --> 00:03:50,800 Speaker 1: Hill says that most booming sounds are heard over a 71 00:03:50,840 --> 00:03:54,200 Speaker 1: limited range, so reports of clusters of booming sounds separated 72 00:03:54,240 --> 00:03:57,680 Speaker 1: by large distances are most likely coming from multiple sources. 73 00:03:58,120 --> 00:04:00,760 Speaker 1: The exceptions, he says, a main clue the sound from 74 00:04:00,840 --> 00:04:03,600 Speaker 1: a meteorite exploding in the atmosphere high above the Earth, 75 00:04:03,920 --> 00:04:07,400 Speaker 1: a massive volcanic eruption, or an aircraft flying it's supersonic 76 00:04:07,440 --> 00:04:15,640 Speaker 1: speeds for an extended distance. Today's episode was written by 77 00:04:15,680 --> 00:04:18,719 Speaker 1: Patrick Jake Haiger and produced by Tristan McNeil. For more 78 00:04:18,720 --> 00:04:21,320 Speaker 1: on this and lots of other mysterious topics, visit our 79 00:04:21,400 --> 00:04:34,600 Speaker 1: home planet, how stuff Works dot com.