A Reader Writes: Dear Signs,
Here is my attempt at a virtual sky watch, using internet sources to try and get a handle on the level of fireball and meteor impact activity happening around the world. I started this in late 2002 when I became intrigued by an apparently anomalous cluster of fireballs and meteorite impacts that were reported [in the] Signs report. I became curious about the data available on the frequency of fireballs, particularly in light of the idea of a 3600 year meteor swarm cycle.[...]
As I have noted previously in an email to Laura, the two most extensive fireball reporting sites, the International Meteor Organization and the American Meteor Society,with extensive databases for the World and North America respectively, ceased reporting their data in 2001. My emails to addresses listed for the fireball pages of these sites were returned as undeliverable. Hmmm.
I am using four web database sources, listed below, in addition to Alltheweb and Google searches for miscellaneous individual reports from numerous sources. I then cross check all the reports in an attempt to eliminate duplicate sightings of the same event.
The four databases I am using are:
1.) Society of Popular Astronomy. Generally covers western Europe.
2.) Univ. of Regina Covers Canada.
3.) Alien Dave Covers Utah, USA
4.) Unione Astrofili Italiani Covers Italy and environs and includes brilliant meteors.
These databases present data consistently for the period from October, 2001 to present, with the exception of Society of Popular Astronomy where data is available only from January, 2002 to present, and this site has not been updated since July 2, 2003.
Results as currently tabulated:
* No SPA Data available.
Key, one symbol = one event:
+ Unione Astrofili Italiani (Italy and environs)
C University of Regina (Canada)
E Society of Popular Astronomy (Western Europe)
M Miscellaneous Internet reports, also includes Alien Dave reports (Miscellaneous and Utah, USA)
The data is not particularly enlightening at this point because of the relatively short time period covered, and especially without current AMS and IMO data. For example, there were about 33 fireball events reported for North America alone in the July, 2001 AMS data for North America. These two sites were the most systematic available, besides the Italian site, because they include online report forms, and they were clearly utilized by enthusiastic sky watchers.
The most intriguing features in my eye are the significantly higher summer/fall peak for 2003 as compared to 2002 and the apparent late winter/spring peak in 2002/2003, clearly higher than the same period in 2002.
Let me know if this is of interest to you and I will send future updates.
A Reader Writes: I was surfing the net and thought it would be interesting to do a little comet counting. Here are a couple of articles from spaceref.com:
2/8/2000 The record is to comet-hunting what Mark McGwire's home-run streak is to baseball: In just four years of operation, the Solar and Heliospheric Observatory (SOHO) spacecraft has found 102 comets, making it by far the most successful comet-hunter in history.
That's a 102 comets discovered in the first 4 years. Then another 398 discovered in the next 2 and half years.
On Monday 12 August 2002, about 16.05 UT, ESA's SOHO spacecraft spotted its 500th comet as the comet passed close to the Sun. This site is keeping track of all comet discoveries since 1990:
Things were pretty quiet until 1996 and then in 1998 there was a big jump in discoveries. It seemed to peak last year with 153
discovered. There is a sudden drop off for 2003, with only 31 discovered so far. SOHO has discovered 64 since last August.
Could this be the calm before the storm?
By JACK KAPICA
Globe and Mail Update
Want to protect your data? Send it to the moon.
A company called TransOrbital of La Jolla, Calif., is seriously considering the idea of putting storage facilities on Earth's only natural satellite, says a report in PC Magazine. [...]
The moon is a pretty safe place to store your data," said Mr. Laurie. "Sept. 11 caused people to think about what data backup really means, and there is also always the threat of a natural disaster here on earth, such as a small asteroid hitting the planet." [...]
[...]Jim Benson, founder, chairman and chief executive of SpaceDev. "This study picks up where we left off from our original 1997 Near Earth Asteroid Prospector (NEAP) mission design, our 1999 Mars MicroMission design for NASA's JPL, and our work in 2001 with Boeing on possible commercial lunar orbiter missions." [...]
Dear Friends and Students of NEOs:
Once again, the press are reporting that the asteroid impact hazard has decreased. It seems as if every published scientific paper on asteroid science is instantly interpreted as a change in the hazard. But this is not necessarily so.
This edition of NEO News focuses on two related issues: the risk from impact by NEAs (Near Earth Asteroids) less than 1 km in diameter, especially the risk from impact tsunami, and the atmospheric breakup of NEAs with diameter less than 200 m. [...]
I find it curious that the publication of various models of NEA populations and (in this case) of atmospheric penetration are interpreted in the press as changes in the impact hazard. However, few have reported the very real decrease in the hazard that results from the steady progress of the Spaceguard Survey in discovering NEAs larger than 1 km, which is where most of the hazard lies and where we are making the greatest progress in reducing this hazard. [...]
NASA astronomers use a new camera to discover a near-Earth object.
by Jeremy McGovern
NASA's Near-Earth Asteroid Tracking (NEAT) team scans the sky for potentially hazardous asteroids using the fledgling QUEST ( Quasar Equatorial Survey Team) camera at California's Palomar Observatory. While this camera is in the infancy of its career, the QUEST instrument has already proven invaluable in the hunt for sun-orbiting rocks in our solar system.[...]
"We expect the new camera to increase the efficiency of detection of near-Earth asteroids by some 3 to 4 times that of the camera it replaced," explains Raymond Bambery, NEAT's principal investigator. "This will make a major contribution to NASA's goal of discovering more than ninety percent of near-Earth objects that are greater that .62 mile (1 km) in diameter by 2008."
Comment: A catalogue of many historical accounts of meteors and asteroids falling all over the earth such as this one:
Stone-fall; many large ones; flames in sky and great detonations. Kangra, N.E. of Lahore, india. For an account of this remarkable fall, see the "Times" newspaper, end of December 1860.
A series of shocks and explosions frightened the inhabitants, and shook the mountains; all the phenomena painfully sublime and alarming; lasted a long time; to the noises succeeded flames of fire (12 feet long?), like the flames from a cannon-mouth; then a great shower of meteoric stones ploughed up the earth in numbers. Another account says the fall took place at Dharamsala, July 14. A great fiery body was seen, then a great detonation, which shook the ground, followed by 14 or 15 smaller ones.
One stone was picked up which was so intensely cold as to benumb the fingers and hands. See Haidinger's paper in the 42nd volume of the Transactions of the Imperial Academy of Vienna. Specimens are being sent to Europe.
By Seth Shostak
posted: 07:00 am ET
24 July 2003
Jayant Narlikar, of the Inner-University Centre for Astronomy and Astrophysics in Pune, India, claims to have data in support of panspermia. Narlikar recently flew an experiment in a high-altitude balloon. On board was a cryogenic sampler consisting of 16 cylinders that were pumped out and decontaminated before launch. As the balloon climbed into the Indian sky, puffs of air were sucked in. One by one, the cylinders were automatically filled with samples from various altitudes, ranging from 25 to 41 km.
Once the payload returned to Earth, it was examined in biology labs in Cardiff and Sheffield, England. To their amazement, the researchers found evidence for live cells in the samples from 41 km. Even more interesting, these "bacteria" recovered at high altitude were non-culturable. This doesn’t mean that they didn’t appreciate opera, but rather that they couldn’t be grown in laboratory Petri dishes. According to Narlikar, this was important in ruling out laboratory contamination of the samples – the cells found were clearly not a common lab bacterium.
New Haven, Conn. -- Yale researchers working with colleagues at Indiana University have added a giant electronic camera to a veteran telescope at Palomar observatory that will be used to look for distant galaxies, supernovae, asteroids and other objects in the sky.
[...] The QUEST team used a similar camera to find the distant, frozen planet known as Huya. Huya is about one quarter the size of the planet Pluto and one of the biggest objects to be found in our solar system since Pluto was discovered in 1930. It resides in the Kuiper Belt located beyond Neptune.
In addition to looking for more Kuiper Belt objects, astronomers plan to use the camera in the drift scan mode to find objects that might be quasars, which are very bright cores of distant galaxies that are thought to contain supermassive blackholes.
Astronomers from the University of Cambridge, UK, have found for the first time the true outer limits of a galaxy. They have also shown that the dark matter in this galaxy is not distributed in the way conventional theory predicts.
[...] In one dwarf spheroidal, found in the constellation Ursa Minor, the team found a clump of slow-moving stars near the galaxy's centre. They interpreted this clump as the remains of a group of stars known as a globular cluster.
This group of stars flies in the face of the most popular model for how dark matter is distributed in galaxies. The 'lambda cold dark matter' model, which explains very well the large-scale structures in the Universe, predicts that dark matter rapidly increases in density towards the centre of a galaxy. If dark matter were distributed in this way in the Ursa Minor dwarf spheroidal galaxy, the star cluster would have been dispersed. The cluster's existence shows that the dark matter is in fact distributed differently in this galaxy.
TORONTO (CP) - A pair of Canadian astronomers and an American scientist have for the first time measured the shape and size of dark matter surrounding galaxies and its effect on light emitted from more distant sources - findings that tip the scale in favour of the existence of the mysterious substance.
The existence of dark matter has been hotly debated among astronomers for years. It's believed to comprise about 25 per cent of the total mass of the universe, with the rest consisting of normal matter (five per cent) and dark energy (70 per cent). Dark energy is believed to push particles apart, contributing to the expansion of the universe.
By Leonard David
Senior Space Writer
posted: 07:00 am ET
29 July 2003
PASADENA, California – The two moons of Mars – Phobos and Deimos – could be the byproducts of a breakup of a huge moon that once circled the red planet, according to a new theory.
The capture of a large Martian satellite may have taken place during or shortly after the formation of the planet, with Phobos and Deimos now the surviving remnants.
Comment: The following comment from the C's does not rule out the above.
Q: (L) What are Mars' moons?
A: Disguised bases.
Q: (L) Who built them?
A: Who else? The Lizzies.
A few months ago, there was some discussion on the Internet that there had been no new photos of one of the moons for several years. Do any of our readers know whether this is true, or is it disinfo?
By Irene Brown, Discovery News
[...]A quest for oil in the North Sea has turned up an ancient impact crater so well preserved that it could give scientists fresh insight into the effects of large meteorite impacts on Earth. The 12-mile wide crater is buried under 120 feet of water and more than 900 feet of sediment, which has helped preserve features that on Earth's surface would have been eroded away. [...]
Diario 'Los Andes' - Mendoza Province, Argentina
Despite the fact that an extensive region from San Rafael to Malargue was combed by air -- reaching the border with Neuqun province--no traces were found of the meteorite which plunged to Earth in the early hours of Friday morning in southern Mendoza.
The failed mission nonwithstanding, the head of the Instituto Coprnico, Jaime Garc,a--a renown scientist and astronomre--claims having no doubt that something fell from space: "If we didn't find it today, will continue looking in other areas we didn't survey," he said. [...]
Impact lethality and risks in today's world: Lessons for interpreting Earth history
Clark R. Chapman
Southwest Research Institute
Abstract: There is a modern-day hazard, threatening the existence of civilization, from impacts of comets and asteroids larger than about 1.5 km diameter. The average annual world fatality rate is similar to that due to significant accidents (for instance, airliner crashes) and natural disasters (e.g. floods), although impact events are much rarer and the deaths per impact event are much greater. (Smaller, more frequent impacts can cause regional catastrophes from tsunamis of unprecedented scale at intervals similar to the duration of recorded human history.)
As the telescopic Spaceguard Survey census of Near Earth Asteroids advances, numerical simulations of the dynamical and collisional evolution of asteroids and comets has also become robust, defining unambiguously past rates of Earth impact of larger, more dangerous cosmic bodies. What are very tiny risks for impacts during a human lifetime become certainties on geological timescales. Widely reported errors in predictions of possible impacts during the next century have no bearing on the certainty that enormous impacts have happened in the past.
The magnitudes and qualitative features of environmental consequences of impacts of objects of various sizes are increasingly well understood. Prime attributes of impacts, not duplicated by any other natural processes, are: (a) extreme suddenness, providing little opportunity for escape and no chance for adaptation, (b) globally pervasive, and (c) unlimited potential (for K/T-boundary-scale impacts and larger) for overwhelming destruction of the life-sustaining characteristics of the fragile ecosphere, notwithstanding the rather puny evidence for impacts in the geological record.
A civilization-ending impact would be an environmental and human catastrophe of wholly unprecedented proportions. K/T-scale impacts, of which there must have been at least several during the Phanerozoic (past 0.5 Gyr), are 1,000 times still more destructive. No other plausible, known natural (or man-made) processes can approach such catastrophic potential. The largest impacts must have caused mass extinctions in the fossil record; other natural processes could not have done so. Perspectives concerning both (a) the potential modern-day destructive potential of impacts and (b) conceivable, almost miraculous refugia in our own world provide a new gestalt for thinking about past cataclysms. [...]
Diario 'Los Andes' - Mendoza
By Teresita Sancho
Translation © 2003 Scott Corrales, Institute of Hispanic Ufology (IHU)
The area where the meteor which frightened residents in southern Mendoza last Friday morning has been logged. The place was determined through the account of a rancher on the banks of the Diamante River, who described in detail the direction of the possible impact site of at least one of the sizeable chunks of rock.
"A brightness with a reddish blue light almost left us blind. It was followed by a very loud report and the earth shook. In the early morning we saw lots of smoke which lingered until lunchtime," said the famer, a privileged witness to the phenomenon. "It wasn't far from the house. Some leagues, maybe two days' on horseback," he added, when asked about the distance. This description agrees with the one given by some fishermen at the Agua del Toro dam.
The explanation--particularly the reference regarding the smoke, which no one had mentioned as of yet--gave Hector Correas, the head of Civil Defense, the possibility to determine the impact site: "It would be in the southern part of Cerro El Diamante, facing the Picasa Mine, some 100 km south in a straight line from the city of San Rafael," explained the official, noting that this is a rough, mountainous area where several private ranches can be found. [...]
While Hollywood has explored the possibility of an asteroid or comet colliding catastrophically with the Earth, off-screen there are no plans for civil defense in case an unexpected impact occurs, no international agreements on how to respond if a threatening asteroid is detected, and no current studies of deflection technology. Although the probability of a fatal impact is extremely small, the consequences would be so great that it is necessary to understand and establish realistic societal goals, scientists said at the 2003 annual meeting of the American Association for the Advancement of Science (AAAS), held this year in Denver. [...]
About 2000 such objects are believed to exist in near-Earth space. Between a quarter to one-half of them will eventually impact the Earth. But the average interval between such impacts is long--more than 100,000 years. One of the more notable impacts occurred in 1908, when a relatively small asteroid struck Tunguska, Siberia, downing hundreds of miles of forest. [...]
BY MARK ALPERT
PM Illustration by Paul DiMare
[...]Recently declassified Cold War era data compiled by scientists at the Los Alamos National Laboratory (LANL), in New Mexico, suggest the Earth takes more nuclear-weapon-sized hits than previously believed. In the '80s, scientists estimated that a doomsday rock was a once-in-100-million-years event. The "new" data--which was drawn from a network of ultrasensitive sensors designed to locate nuclear blasts--reduces the odds to once every 10 million years.
And it isn't just these planet-crushers we have to worry about. A small object can cause a tremendous amount of damage. The data revealed that a 7-ft. object can produce a 1-kiloton blast, the equivalent of igniting 1000 tons of high explosives. Between 1975 and 1992, the sensors detected the sonic signatures of 136 explosions ranging in size from 1/2 kiloton to a Hiroshima-sized 15 kilotons.
In 1990, Congress ordered NASA to study the threat posed by asteroids and comets. [...]
Comment: The article continues with various methods scientists have been discussing in dealing with NEO's on a collision course, some sound like they come from a science fiction novel. The article is from Popular Mechanics. The same magazine that promised we would have flying cars by the turn of the century.
August 10, 2003
Fragments of what could be a meteorite which narrowly missed a 10-year-old boy when it smashed into his driveway would be scientifically tested in Perth, the youngster's mother said today.
Anthony Elliss-Galati saw an odd-shaped object in the sky, heading towards him on Thursday as he played outside his Safety Bay home, about 50km south of Perth. Anthony told his mother Jennifer Elliss he hid behind her car and watched the bird-sized object smash a hole in the driveway and shatter.
"I heard something hit the bitumen and then Anthony came inside and said there were rocks coming out of the sky," Ms Elliss said. "He then handed me a piece and it didn't look like a normal rock - it was dull on the inside and silver on the outside and looked as if it had melted."
Ms Elliss said she went outside and was surprised at the large hole the flying debris had left. "Anthony said he had seen it coming across the park and had to duck down behind my car to avoid being hit by it," she said.
Ms Elliss said although it was not massive, she believed the object was a meteorite. "The pieces look exactly like a real meteorite I saw when I was a kid."
Ms Elliss has contacted the WA Museum and the Perth Observatory and will be taking the fragments to Perth tomorrow to have them scientifically tested.
Comment: It is startling to see the amazing lack of media attention given to the rapidly increasing number of fireballs and even small meteorite hits that get very little attention other than a dry report as though this were "normal."
July 5 2001:
Q: [Can you] describe to us, the catastrophic situation in our future, our near future?
A: It seems as though it will be a progression. Like the beginning of rain, when the first few big, cold drops fall; and then a pause followed by a few more drops; and then, a downpour. [...] I see rocks - but they aren't very large. They are like the size of your fist. Just a few. And they make something of a stir. An uproar. People will be excited... very upset. It looks like just two - two small rocks. And then nothing else happens for awhile, and then they forget about it. It all dies down. And then, a third, a fourth, a fifth and a sixth - and maybe even a seventh... isolated events, or so it seems. Still small.
And then, a big one.
All this will go on over a period of months.
EUROPEAN SPACE AGENCY NEWS RELEASE
Since early 1992 Ulysses has been monitoring the stream of stardust flowing through our Solar System. The stardust is embedded in the local galactic cloud through which the Sun is moving at a speed of 26 kilometres every second. As a result of this relative motion, a single dust grain takes twenty years to traverse the Solar System.
Observations by the DUST experiment on board Ulysses have shown that the stream of stardust is highly affected by the Suns magnetic field.
In the 1990s, this field, which is drawn out deep into space by the out-flowing solar wind, kept most of the stardust out. The most recent data, collected up to the end of 2002, shows that this magnetic shield has lost its protective power during the recent solar maximum.
In an upcoming publication in the Journal of Geophysical Research ESA scientist Markus Landgraf and his co-workers from the Max-Planck-Institute in Heidelberg report that about three times more stardust is now able to enter the Solar System.
The reason for the weakening of the Suns magnetic shield is the increased solar activity, which leads to a highly disordered field configuration. In the mid-1990s, during the last solar minimum, the Suns magnetic field resembled a dipole field with well-defined magnetic poles (North positive, South negative), very much like the Earth.
Unlike Earth, however, the Sun reverses its magnetic polarity every 11 years. The reversal always occurs during solar maximum. Thats when the magnetic field is highly disordered, allowing more interstellar dust to enter the Solar System.
It is interesting to note that in the reversed configuration after the recent solar maximum (North negative, South positive), the interstellar dust is even channelled more efficiently towards the inner Solar System. So we can expect even more interstellar dust from 2005 onwards, once the changes become fully effective.
While grains of stardust are very small, about one hundredth the diameter of a human hair, they do not directly influence the planets of the Solar System. However, the dust particles move very fast, and produce large numbers of fragments when they impact asteroids or comets.
It is therefore conceivable that an increase in the amount of interstellar dust in the Solar System will create more cosmic dust by collisions with asteroids and comets.
We know from the measurements by high-flying aircraft that 40,000 tonnes dust from asteroids and comets enters the Earths atmosphere each year. It is possible that the increase of stardust in the Solar System will influence the amount of extraterrestrial material that rains down to Earth.
The article mentions the potential danger from a galactic dust storm:
[...]The effect this will have on our planet - if any - is unknown. But some researchers have speculated that sustained periods of cosmic dust bombardment might be related to ice ages and even mass extinctions.[...]
From today's article, it sounds like the dust storm creates something like a feedback loop, increasing the amount of dust and subsequently the amount of dust that enters the earth's atmosphere...
By Tom Greenwood
The Detroit News
DAVISBURG -- Live long and prosper -- and duck!
The Road Commission for Oakland County may have had a close encounter of the shooting-star kind when what appears to be a meteorite hit one of its maintenance facilities over the weekend. [...]
Number of new moons goes sky high
Henry Fountain NYT
Tuesday, August 12, 2003
Not too long ago, it was easy for an armchair astronomer to keep up to speed on the moons of the solar system. There was the Moon, of course, and the four Jovian satellites spotted by Galileo, those two around Mars, and some odd ones here and there - that weird fractured cue ball orbiting Uranus, for instance.
These days, though, it is tough to tell the moons without a scorecard. In the past six years, dozens of satellites have been discovered around the giant planets, more than doubling the total in the solar system. Jupiter is the current leader, with 61, followed by Saturn, Uranus and Neptune. The tally for these four planets is 124 (the other five planets have only four among them), but that number is sure to change in the next year or two.
"They're all over the place," said Dr. Brett Gladman, an associate professor at the University of British Columbia who has been involved in the discoveries since 1997.
The new moons are very small, many just a couple of miles in diameter, and carve distant, eccentric paths around their planets. Many orbit in retrograde fashion, in a direction opposite to their planets' rotations.
They have little in common with the large moons in the solar system - none of the volcanoes of Jupiter's Io or the atmosphere of Saturn's Titan, or the massive rifts of Uranus's Miranda. Many don't even have names yet. They are little more than orbiting rocks. [...]
for National Geographic News
August 11, 2003
Science has a better understanding of how and when the moon came to be thanks to a team of German geochemists who compared ratios of trace elements in rocks from the Earth, the moon, Mars, and meteorites.
Most astronomers subscribe to the so-called "cratering" theory to explain the moon's creation: Billions of years ago, a Mars-sized body slammed into Earth, projecting a mixture of rocky debris into space, some of which lumped together to form the moon. The remaining debris rained back down on Earth. [...]
Asteroid has a 'bite' out of it
HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS NEWS RELEASE
Posted: August 12, 2003
If someone sneaks a bite of your chocolate chip cookie, they leave behind evidence of their pilferage in the form of a crescent of missing cookie. The same is true in our solar system, where an impact can take a bite out of a planet or moon, leaving behind evidence in the form of a crater. By combining modern technology with a historical telescope, astronomers have discovered that the asteroid Juno has a bite out of it. The first direct images of the surface of Juno show that it is scarred by a fresh impact crater. [...]
MOUNT VERNON [PACIFIC NW, USA] - A local couple has an out of this world tale to tell, and the proof it really happened.
On May 1, Mark and Gail Fredlund were in their back yard checking the hummingbird feeder when they heard it coming.
"All of the sudden the loud whizzing sound came right by our heads," said Gail.
That whizzing sound landed on their garden edging, leaving quite a dent, and then bounced onto the lawn.
"This is a rock, that came out of the air, on a blue sky day like this, they don't have wings, so it had to be a meteor," said Mark.
Gail called the experts at the University of Washington who asked her if she'd done "the test." Just hang a magnet on a thread, then hold the rock near it.
If the magnet sticks to the rock, there's a good chance it's a meteorite.
The Fredlund's galactic gift passed the initial test, and now, UW investigators have concurred that the rock is likely a meteorite. The couple will take the rock to them next month. [...]
By Helen Briggs
BBC News Online science reporter
4 September, 2002
This is the sharpest-ever picture of an asteroid making a close approach to the Earth.
At the time, the space rock was 400 metres (a quarter of a mile) across and could be seen with binoculars or a small telescope. The nearest it came was 750,000 kilometres (466,028 miles) of the Earth - twice the distance to the Moon.
Astronomers say the asteroid, known as 2002 NY40, posed no danger to life on Earth. But if it had hit our planet, the force would have been equivalent to that of several nuclear bombs. [...]
Credit & Copyright: Ivan and Colby Navarro
If you wait long enough, a piece of outer space itself will come right to you. As Colby Navarro worked innocently on the computer, a rock from space crashed through the roof, struck the printer, banged off the wall, and came to rest near the filing cabinet. This occurred around midnight on March 26 in Park Forest, Illinois, USA, near Chicago. The meteorite, measuring about 10 cm across, was one of several that fell near Chicago that day as part of a tremendous fireball.[...]
Comment: The link shows a photo of the meteorite's destructive path through the house. Also see: Meteorites Fall on Chicago Suburbs: Pieces of extraterrestrial rock crash-landed near Chicago after a bolide exploded in Midwestern skies early Thursday morning, March 27, 2003.
On October 9, 1992, a fireball was seen streaking across the sky from Kentucky to New York. At least 14 people captured part of the fireball on videotape; here is a spectacular MPEG movie (1 MB MPEG) of the fireball (source) . A 12-kilogram stony meteorite (chondrite) from the fireball fell in Peekskill, New York, smashed the trunk of a parked automobile, and came to rest beneath it. These are the first motion picture recordings of a fireball with an associated meteorite fall. Here is a short MPEG movie of a -4 magnitude Delta Capricornid fireball (253 kB MPEG) recorded near Hannover, Germany, on January 5, 1995
[...] Provided the meteoroid does not burn up entirely, the rock (or fragments of it, if it exploded) falls to the surface of the earth, at this point having a speed no greater than any object falling to earth due to gravity. Enormous meteoroids can travel through the atmosphere without being slowed down, their great momentum overcoming the force of friction with the air, and strike the earth with such force as to cause an impact crater. Numerous craters on the earth's surface are known to have been caused by collisions of this sort, but these occurrences are rare.
The fall of a meteorite is quite a spectacle. Observers have reported coloured flashes in the sky that turn night to daylight, multiple explosions, and unusual crackling and thundering sounds both before and after the sighting. Near the actual fall, the sound of fragments breaking off the stone has been heard, as has the whistling of the falling stone and the thud of impact. On rare occasions, meteorite falls have caused damage or injury, but none of the meteorites recorded in Canada have done so.[...]
Astro Notes June/July 1998
Once in a while you read that a meteorite has hit a building or car. Or landed on the ground next to someone. Why has it never happened to you? The Canadian Meteorite Observation and Recovery Project (MORP) that operated on the prairies from 1974 to 1985 recorded meteorite falls and Halliday et al. (1989) established from the MORP data that ~7,000 meteorites weighing more than 1 kg fall on the Earth each year (note that these are masses on the ground, not pre-atmospheric masses). However, only about five meteorites are recovered as fresh falls each year. Why only five? [...]
Aug. 25 - A meteorite whose age is estimated at millions of years was discovered near Timna in the Arava, Maa'ariv reported. The space rock was checked by laboratories at the University of California in Los Angeles (UCLA). The laboratory's report said that the tiny stone landed in Israel only "several decades or several hundred years ago."
The stone, whose outside is black and scorched and is mingled with brown and light gray, weighs 40 grams and is the size of two walnuts. [T]he test showed that it was a fragment of Asteroid HAVH-6, a rocky heavenly object that departed from its orbit between the sun and Jupiter, and broke up. The original asteroid approaches the earth once every three years. [...]