Netherlands fireball

[neufer]

Netherlands fireball
By Emily Lakdawalla Oct. 14, 2009


Fireball over the Netherlands, October 13, 2009

<<Robert Mikaelyan acted fast as a bright meteor streaked across the sky at about 19:00 local time (17:00 UTC), snapping six photos of the meteor over three seconds. Credit: Robert Mikaelyan, Groningen, The Netherlands>>

[neufer]

http://apod.nasa.gov/apod/ap091015.html

• Infrasound detection of Netherlands bolide
  
  An infrasound array, designed to listen for ground-shaking events,
  apparently detected the explosion of the Netherlands bolide
  witnessed by thousands on October 13, 2009.
  Credit: Läslo Evers, KNMI

<<Infrasound is sound that is lower in frequency than 20 Hz (Hertz) or cycles per second, the normal limit of human hearing. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high. The ear is the primary organ for sensing infrasound, but at higher levels it is possible to feel infrasound vibrations in various parts of the body. The study of such sound waves is sometimes referred to as infrasonics, covering sounds beneath 20 Hz down to 0.001 Hz. This frequency range is utilized for monitoring earthquakes, charting rock and petroleum formations below the earth, and also in ballistocardiography and seismocardiography to study the mechanics of the heart. Infrasound is characterized by an ability to cover long distances and get around obstacles with little dissipation.

Infrasound sometimes results naturally from severe weather, surf, lee waves, avalanches, earthquakes, volcanoes, bolides, waterfalls, calving of icebergs, aurora, lightning and upper-atmospheric lightning. Nonlinear ocean wave interactions in ocean storms produce pervasive infrasound vibrations around 0.2 Hz, known as microbaroms. Scientists accidentally discovered that the spinning core or vortex of a tornado creates infrasonic waves. When the vortices are large, the frequencies are lower; smaller vortices have higher, though still infrasonic, frequencies. These low frequency sound waves can be detected for up to 160 kilometres (100 mi) away and can help provide early warning of tornadoes. Infrasound can also be generated by man-made processes such as sonic booms and explosions (both chemical and nuclear), by machinery such as diesel engines and older designs of down tower wind turbines and by specially designed mechanical transducers (industrial vibration tables) and large-scale subwoofer loudspeakers. The Comprehensive Nuclear-Test-Ban Treaty Organization uses infrasound as one of its monitoring technologies (along with seismic, hydroacoustic, and atmospheric radionuclide monitoring).

Possibly the first observation of naturally occurring infrasound was in the aftermath of the 1883 eruption of Krakatoa, when concussive acoustic waves circled the globe seven times or more and were recorded on barometers worldwide. Infrasound was also used by Allied forces in World War I to locate artillery. One of the pioneers in infrasonic research was French scientist Vladimir Gavreau, born in Russia as Vladimir Gavronsky. His interest in infrasonic waves first came about in his lab during the 1960s, when he and his lab assistants experienced pain in the ear drums and shaking lab equipment, but no audible sound was picked up on his microphones. He concluded it was infrasound and soon got to work preparing tests in the labs. One of his experiments was an infrasonic whistle.

Whales, elephants, hippopotamuses, rhinoceros, giraffes, okapi, and alligators are known to use infrasound to communicate over distances—up to hundreds of miles in the case of whales. It has also been suggested that migrating birds use naturally generated infrasound, from sources such as turbulent airflow over mountain ranges, as a navigational aid. Infrasound may also be used for long-distance communication in African elephants. These calls range from 15–35 Hz and can be as loud as 117 dB, allowing communication for many kilometres, with a possible maximum range of around 10 km (6 mi). These calls may be used to coordinate the movement of herds and allow male elephants to find mates. Elephants also produce infrasound waves that travel through solid ground and are sensed by other herds using their feet, although they may be separated by hundreds of kilometres. Animals perceive the infrasonic waves carried through the earth by natural disasters and can use these as an early warning. A recent example of this is the 2004 Indian Ocean earthquake and tsunami. Animals were reported to flee the area long before the actual tsunami hit the shores of Asia. It is not known for sure if this is the exact reason, as some have suggested that it was the influence of electromagnetic waves, and not of infrasonic waves, that prompted these animals to flee.

When testing human hearing, pure sine wave tones are perceived as less musical near the bottom of the hearing range. Between 10 Hz and 20 Hz, such tones cease being heard as a musical tone unless they are boosted greatly in volume. Below 10 Hz it is possible to perceive the single cycles of the sound, along with a sensation of pressure at the eardrums. Infrasound has been known to cause feelings of awe or fear in humans. Since it is not consciously perceived, it can make people feel vaguely that supernatural events are taking place. Some film soundtracks make use of infrasound to produce unease or disorientation in the audience.>>

[emc]

The visual inspires cosmic awe, the sparked low frequency is intriguingly interesting and the Science is enlightening. Thanks Art!

[bystander]

Nice catch, Art.

[neufer]

Nice catch, Art.

• Who says APOD isn't up to date?
  ---------------------------------------------------------
  . The Comedy of Errors > Act III, scene II
  
  DROMIO OF SYRACUSE: Upon her nose all o'er embellished
  . with rubies, carbuncles, sapphires, declining their rich
  . aspect to the hot breath of Spain; who sent whole
  . armadoes of caracks to be ballast at her nose.
  
  ANTIPHOLUS OF SYRACUSE: Where stood Belgia, the Netherlands?
  ---------------------------------------------------------

[mike lynch]

I saw an IDENTICAL sight over Minnesota in the 1970s.
That object took several minutes (It seemed like 5-10 minutes) to cross the sky (from south to north), disintegrating slowly as it progressed.
Setting in the north - not coming down to earth.
Because it was seen by so many people, it was mentioned in the news over the next few days.

Eventually it was reported to be a Russian satellite reentering earth's atmosphere as expected and that Russia had alerted NASA (or US gov.) in advance
Months later I read about Russian satellite remains that were found in Canada.
I believed it was from the same satellite, but I may have been mistaken.

So I wonder if these images might actually be of a satellite rather than a meteor.
I understand that meteors typically travel at very fast speed and so the series of photos might not be possible if that were the case.
(The flash would be gone before the photographer could react.)

However, I did not hear any sound when I watched that satellite breakup so that may be a critical difference
-Mike Lynch

[ta152h0]

Just imagine ancient insomniacs seeing something like this and renering a visual description on a rockwall... sort of an ancient van Gogh.

[BMAONE23]

I saw something similar back in 2003. I was leaving for work on saturday Feb 1 at 6:00am and saw this object (very similar in appearance) breaking up and leaving a smoke trail as it progresed toward the east. It wasn't until I got to work and turned on the radio that I learned it was actually the Columbia on it's doomed reentry.

[FrankV]

Here's a video of the meteor over Eindhoven (airport cam), it was visible for only 5 seconds or so, very fast moving according to many witnesses:

http://www.youtube.com/watch?v=YPrk54wcZPc

A large portion of these witnesses were on the footballfield, because Tuesday evening (7 pm) is a typical time for amateur football trainings throughout the Netherlands (virtually every village has a football club over here).

[Chris Peterson]

I saw an IDENTICAL sight over Minnesota in the 1970s.
That object took several minutes (It seemed like 5-10 minutes) to cross the sky (from south to north), disintegrating slowly as it progressed.

Your memory is probably playing some tricks on you here. The lowest speed that space junk can reenter is about 7 km/s; the lowest speed it can move and still produce light from ablation is about 2 km/s. Given the maximum distance before an object at high altitude will be over the horizon, the maximum time an object could be observed is about 200 seconds, and that would only be under ideal circumstances. Reentering space junk is normally observed for no more than a couple of minutes in the rare cases where it travels hundreds of kilometers without burning up completely.

So I wonder if these images might actually be of a satellite rather than a meteor.

While the sort of breakup seen is common for space junk, this meteor appears too fast for that. Decaying junk is very rare compared with natural fireballs; I have thousands of fireballs recorded, and only a handful of them appear to be reentries.

However, I did not hear any sound when I watched that satellite breakup so that may be a critical difference.

You only get sound when an object gets quite low- below about 30 km. Most meteors and space junk burn up before they get that low, but either can produce sounds if it gets lower.

[mike lynch]

Thanks Chris.
I re-read the original post and noted the "6 shots over 3 seconds".
That IS fast.

But I was not mistaken about the amount of time my Russian satellite took When I first spotted it low in the south it was over the Minneapolis airport and I thought I was looking at a plane on fire. But it just kept getting higher and higher in the sky until I realized it was breaking into pieces, with each piece leaving a long persistent tail. The persisting tail of the largest (center) object grew to be approximately two times as long as my outstretched thumb and baby finger tip at arms length, (maybe 1/5 the evening sky view) it passed directly overhead and the fall-away pieces had tails nearly as long and they were also quite persistent too. But the width was narrow -around the size of my thumb at arms length.

If you can think about the amount of time a satellite takes to cross the sky overhead (while lying in an open field on a cloudless night) you can start with that time frame,
Then slow it down due to atmospheric friction and you'll begin to get a sense of that long burn. I was with a buddy and we had a long discussion about what we were seeing while it was happening. ( A MIRV being my best guess.) Then we spent a few minutes just yelling to the neighbors to come out and see it.
-Mike

[JohnD]

Here's a video of the meteor over Eindhoven (airport cam), it was visible for only 5 seconds or so, very fast moving according to many witnesses:

http://www.youtube.com/watch?v=YPrk54wcZPc

A large portion of these witnesses were on the footballfield, because Tuesday evening (7 pm) is a typical time for amateur football trainings throughout the Netherlands (virtually every village has a football club over here).

If that was the same event, where is the black sky, glowing fireballs etc of the original pic?
John

[geckzilla]

I don't know for sure if that's the same meteor but I can easily see it being the same one. It's just two different exposures. The video one has to take in a lot more light and is probably designed to take in extra light so you can see the maximum of what's going on while the photographer (who must have had lightning response time) set his camera up so that it wouldn't overexpose or blur the meteor. So that made the sky look dark blue. You can see in his photo it's not black as it would probably be if it were night.

[bystander]

Sunset 2009 Oct 13: Groningen 6:42 pm, Eindhoven 6:49. Picture was taken about 7:00 pm. Don't know the time on the video.

[Brem]

Here's a link to the complete set, 6 photo's:
http://www.fotoarena.nl/index.html