Meteors

"There is no man so dull, so obtuse, so turned to earthly things, who does not direct all the powers of his mind towards things Divine when some novel phenomenon appears in the heavens... The host of heavenly constellations beneath the vault of heaven, whose beauty they adorn, attract no attention; but if any unusual appearance be noticed among them, at once all eyes are turned heavenwards... men forget other objects to inquire about the new arrival; they know not whether to wonder or to tremble”.~(Senecca)

UPDATE: Geminid Meteor Shower - December 15, 2009

On Dec. 13th, Earth passed through a stream of debris from extinct comet 3200 Phaethon. The encounter produced a surge of more than 160 Geminid meteors per hour. The timing of the peak favored observers in Europe and the Middle East, many of whom said it was the finest display of Geminids they had ever seen. See http://spaceweather.com/

Gemini Meteor Gallery

UPDATE: The 2009 Leonid Meteor Shower - November 17 2009

As forecasters predicted, there was a surge of Leonid meteors during the late hours of Nov. 17th. Preliminary counts from the International Meteor Organization exceed 120 meteors per hour. See the Leonid Meteor Shower Gallery at Spaceweather.com

METEOR SHOWERS IN HISTORY

To many, one of the delights of the night sky is the sporadic flash of meteors across the firmament. Most are tiny particles of dust, no bigger than the letters on this page, their brief moment of glory ending in a blaze of light. Their paths seem random and unpredictable and so they are in the main. However, at certain times of the year, a congregation of flashy meteors seems to arrive from the same area of the sky, called the radiant, a matter of perspective only.

Radiants are named for the constellation from which they seem to come and sometimes after a bright star that lies near the radiant. For instance, the Leonids and the delta Aquarids. On a dark night, an observer will see an average of 10 - 15 meteors per hour and each will last for approximately 0.5 to 1 second. Meteors appear in greater numbers near the end of night, that is, early morning. This is entirely due to the Earth’s orbital motion. The hemisphere facing the direction of the Earth’s motion around the Sun will sweep up meteors moving toward it while the preceding hemisphere relies on those rapid motion meteors that overtake the Earth.

Therefore, the time of greatest concentration is around 0000 hrs to 1200 hrs. The time of around 0600 hrs to 1200 hrs occurs naturally in daylight and radar surveillance of the sky confirms this high frequency of arrivals. These showers are the legacies of comets, tiny particles left behind as the comet streams through the Solar System. Sharing the same orbit as their parent comet, these clouds are intercepted by the Earth at regular intervals.

Throughout history, humankind has thought of the arrival of comets in the heavens as portents of death and pestilence. Defoe, writing in the 1600s recorded “A blazing star or comet appeared for several months before the plague (Great Plague 1664), as there did the year after, a little before the fire (Great Fire of London 1666). The old women and the phlegmatic hypochondriacal part of the other sex, whom I could almost call old women too, remarked, especially afterwards, though not till both those judgements were over, that these two comets passed directly over the city, and that so very near the houses (!!) that it was plain they imparted something peculiar to the city alone...”.

Some of these pestilences were historically, or perhaps more appropriate, hysterically accorded to meteoric influences. They were, like so many of the plagues, sudden and lasted but such a brief time that any such presumed connection comes as no surprise. The so-called sweating sickness of the 15th and 16th centuries was characterised by the above and reoccured three times within 46 years, similar to the return of a meteoric swarm circling the Sun.

Bacon’s Life of Henry the Seventh gives substance to the terror of this period and seems to refer to an extra-terrestrial event. “About this time (1485) in autumn, towards the end of September, there began and reigned in the city, and other parts of the Kingdom, a disease then new; which, by the accidents and manner thereof, they called the sweating sickness. The disease had a swift course, both in the sick body, and in the time and period of the lasting thereof... And as to the time of the malice and reign of the disease ere it ceased, it began about the one and twentieth of September, and cleared up before the end of October...It was a pestilent fever, but, as it seemeth, not seated in the veins or humours, for that there followed no carbunckle, no purple or livid spots, or the like, the mass of the body being not tainted; only a malign vapour flew to the heart and seized the vital spirits...It was conceived not to be an epidemic disease, but to proceed from a malignity in the constitution of the air, gathered by predispositions of seasons; and the speedy cessation declared as much”.

Imagine the awe and wonder, if not fear, that would occur with spectacular meteor showers. One such happening is the Leonid meteor shower which occurs every year but is spectacular roughly every 33 years. The Earth’s orbit intersects the path of the debris from periodic comet Temple-Tuttle each November but because the material is not evenly spread, the densest section, which lies nearest the comet itself, is crossed every 33.25 years. This dense strip of cometary material is thought to be around 35,000 kilometres in width and inclined 17 degrees to the Earth's orbital plane.

There have been many recorded Leonid events throughout the last 1800 years or so, but the spectacular shower of A.D. 902 was especially noteworthy. From Islamic Spain was recorded “In the month Dju-I-Kade of that year, King Ibrahim himself also died and, during the night of his death there was seen in the sky an innumerable mass of stars, which were dispersed like rain, and were cast off to right and left...From this circumstance that year was called the year of the stars".

The Egyptians recorded “From the middle of the night until morning, the stars that are called Schuhub (luminous or shooting) were agitated in an extraordinary way, moving from east to west, and from north to south, in such a manner that a person could not keep his eyes on the sky”.

In 1833, the Leonids exploded upon the world with tens of thousands of meteors and many fireballs as bright as the Full Moon, casting shadows and terrifying the populace of North America. Typical of the hysteria is this passage from a letter by a South Carolina plantation worker later published in the book Our First Century by R.M. Devens in 1876. "I was suddenly awakened by the most distressing cries that ever fell on my ears. Shrieks of horror and cries of mercy, could be heard from most of the negroes of the three plantations, amounting in all to some six or eight hundred...I heard a faint voice near the door calling my name...beseeching me to rise, and saying, "O, my God, the world is on fire!” I then opened the door, and it is difficult to say which excited me most; the awfulness of the scene, or the distressed cries of the negroes. Upwards of one hundred lay prostrate on the ground, some speechless, and others uttering the bitterest of moans, but with their hands raised, imploring God to save the world and them. The scene was truly awful, for never did rain fall much thicker than the meteors fell toward the earth; east, west, north, and south, it was the same."

This particular display heralded the start of the true scientific study of meteor showers and possibly ushered in the start of many religious sects that have lasted to this very day.

Comet Temple-Tuttle was first found in 1866 and the predicted shower of 1866 happened on the nights of the 13th and 14th November. At its peak, over 120 meteors per minute graced the heavens. The years 1867 and 1868 also produced thousands of meteors per hour. There was no great display in 1899 as Jupiter had disturbed the orbit of this stream in 1898, pulling the particles away from the Earth by some two million kilometres.

The years 1932 and 1933 were expected to show a decent event but while 1932 displayed a minor shower, 1933 was a complete fizzer. It was thought that perhaps this shower had run its course, deplete of most of its material. However, in 1966, the mid-western United States were treated to the greatest display of meteors in recorded history. At peak, over 40 meteors per second (144,000 per hour) were said to have stunned their audience. The display was very brief and European observers saw only a modest show.

Comet Temple-Tuttle orbits the Sun in the opposite direction than that of the Earth , therefore so does the stream itself. Each particle intercepted by the Earth will tear through the atmosphere at around 71 kilometres per second, producing bright and rapid meteors. As the cometary material is rather delicate, it tends to burn up in the upper, tenuous reaches of our atmosphere, around 150 km above the surface of the Earth. Many Leonid meteors appear blue or green and a large number produce vapour trails.