Brief history of the Leonid shower 902 AD - the first annecdotal account In 868 AD, the ever changing orbit of a yet undiscovered comet crossed the Earth's orbit on the inside for the first time. The comet's orbit had been gradually changing in previous centuries. Shortly thereafter, in 902 AD, Chinese astronomers and observers in what is now Egypt and Italy reported seeing the first Leonid storm. Numerous accounts would follow in the next centuries: "Stars fell like rain" .

In 868 AD, the ever changing orbit of a yet undiscovered comet crossed the Earth's orbit on the inside for the first time. The comet's orbit had been gradually changing in previous centuries. Shortly thereafter, in 902 AD, Chinese astronomers and observers in what is now Egypt and Italy reported seeing the first Leonid storm. Numerous accounts would follow in the next centuries: . 1630 AD -more annecdotes Johannes Kepler dies on Nov. 15, 1630. At his funeral two days later the Leonids lit up the sky. This was considered as a salute from God - Source: "Tycho and Kepler"

Johannes Kepler dies on Nov. 15, 1630. At his funeral two days later the Leonids lit up the sky. This was considered as a salute from God - Source: 1799 - Meteors puzzle scientist In the Americas observers are startled by many meteors. The reknowed German scientist Humboldt and companion Bonpland, who are in Cumana (Venezuela) at the time, record the event and make it widely known in the scientific community. Rumour has it that in 1766 a similar meteor storm was seen over Cumana. "Tausende von Feuerkugeln und Sternschnuppen fielen hintereinander, vier Stunden lang. (...) Nach Bonplands Aussage war gleich zu Anfang der Erscheinung kein Stück am Himmel so groß als drei Mond Durchmesser das nicht jeden Augenblick von Feuerkugeln und Sternschnuppen gewimmelt hätte. Von 4h an hörte die Erscheinung allmählich auf; ..." - Humboldt

In the Americas observers are startled by many meteors. The reknowed German scientist Humboldt and companion Bonpland, who are in Cumana (Venezuela) at the time, record the event and make it widely known in the scientific community. Rumour has it that in 1766 a similar meteor storm was seen over Cumana. 1833 - The radiant established In 1833, observers are somewhat familiar with Leonid storms. The storm that year is very intense and the event leads to the first formulation of a theory on the origin of meteors.



"On the night of November 12-13, 1833 , a tempest of falling stars broke over the Earth... The sky was scored in every direction with shining tracks and illuminated with majestic fireballs. At Boston, the frequency of meteors was estimated to be about half that of flakes of snow in an average snowstorm. Their numbers... were quite beyond counting; but as it waned, a reckoning was attempted, from which it was computed, on the basis of that much-diminished rate, that 240,000 must have been visible during the nine hours they continued to fall." - Agnes Clerke's, Victorian Astronomy Writer Figure 1: a 19th century woodcut with an impression of the spectacular November 13, 1833 Leonid storm. Courtesy Seventh-Day Adventist Church. Early settlers look up in amazement at a sky filled with shooting stars. John Sharp reports on a contamporary account from the diary of Michael Shiner, Nov. 12 1833: " The Meteors fell from the elements the 12 of November 1833 on Thursday in Washington. It frightened the people half to death."

In 1833, observers are somewhat familiar with Leonid storms. The storm that year is very intense and the event leads to the first formulation of a theory on the origin of meteors. 1866 - METEORS AND COMETS Ernst Tempel and Horace Tuttle independently discover a dim comet. After observing the comet for several weeks, an orbit was calculated. It was found that the orbit was of short period, 33.17 year. In November that year, a Leonid storm was anticipated. The sheer number of meteors startled observers in Europe, who scrambled to count the numerous meteors and determine the radiant position. An orbit was calculated for the meteoroids assuming a period of 33 years, and the similarity with the comet orbit was discovered.

Ernst Tempel and Horace Tuttle independently discover a dim comet. After observing the comet for several weeks, an orbit was calculated. It was found that the orbit was of short period, 33.17 year. In November that year, a Leonid storm was anticipated. The sheer number of meteors startled observers in Europe, who scrambled to count the numerous meteors and determine the radiant position. An orbit was calculated for the meteoroids assuming a period of 33 years, and the similarity with the comet orbit was discovered. 1899 - The disappointment It was now well established that the comet and the meteors returned to Earth every 33 years. The return of 1899 was eagerly awaited. Paris scientists launched a balloon with the first meteor airborne astronomer Dorothea Klumpke. That year, many meteors crossed the sky, but the sharp main peak of past Leonid storms was not observed. The comet also did not show itself again. However, strong activity continued until 1902, with rates increasing to storm conditions in 1901.

It was now well established that the comet and the meteors returned to Earth every 33 years. The return of 1899 was eagerly awaited. Paris scientists launched a balloon with the first meteor airborne astronomer Dorothea Klumpke. That year, many meteors crossed the sky, but the sharp main peak of past Leonid storms was not observed. The comet also did not show itself again. However, strong activity continued until 1902, with rates increasing to storm conditions in 1901. 1933 - Bad weather? In 1932 rates went up again, but a big storm was not observed. At the time, it was thought that the shower was lost because of a close encounter with Uranus prior to the 1899 return. Or, perhaps, the storm was simply missed by the more scientifically oriented observers because of bad weather. Such is not uncommon in the northern hemisphere in the middle of November.

In 1932 rates went up again, but a big storm was not observed. At the time, it was thought that the shower was lost because of a close encounter with Uranus prior to the 1899 return. Or, perhaps, the storm was simply missed by the more scientifically oriented observers because of bad weather. Such is not uncommon in the northern hemisphere in the middle of November. 1965 - Comet P/Tempel-Tuttle Rediscovered Lost for nearly a century, the comet P/Tempel-Tuttle was rediscovered in 1965. Calculations would later reveal that this comet passed closer to the Earth's orbit (0.0032 a.u.) than on any occasion since 1833. Some predicted the return of a storm over Europe. Instead, a tremendous storm of tens of thousands of Leonids fell for a short interval timed by skywatchers in the central and western United States on November 17th, 1966. This display probably rivaled the historic showers of 1799 and 1833. Within just two hours, observed rates increased from about 40 per hour to flurries of as much as 40 per second!



"We saw a rain of meteors turn into a hail of meteors too numerous to count," - Charles Capen in the San Gabriel Mountains of Southern California



"The meteors were so intense that we were guessing how many could be seen in a one-second sweep of the observers head... A rate of about 150,000 per hour was seen for about 20 minutes." - Dennis Milon, Kitt Peak in Southern Arizona

Figure 2: One of many spectacular meteor photographs of the 1966 storm: some 40 Leonids are shown in this 10 to 12 minute exposure by A. Scott Murrell. Read more eye-witness accounts here.

Figure 3: Meteor counts in November of 1993 and 1994 by means of Radio MS from Ilkka Yrjola, Kuusankoski, Finland. A strong spike of activity stands out above the daily variation of sporadic activity.

Lost for nearly a century, the comet P/Tempel-Tuttle was rediscovered in 1965. Calculations would later reveal that this comet passed closer to the Earth's orbit (0.0032 a.u.) than on any occasion since 1833. Some predicted the return of a storm over Europe. Instead, a tremendous storm of tens of thousands of Leonids fell for a short interval timed by skywatchers in the central and western United States on November 17th, 1966. This display probably rivaled the historic showers of 1799 and 1833. Within just two hours, observed rates increased from about 40 per hour to flurries of as much as 40 per second! 1994 - The first Leonid outburst of the new return The first increase of Leonid rates announcing the return of the comet was reported in 1994. Astronomer Peter Jenniskens was among the first to notice the high Leonid rates on November 18 that year, when the shower was as strong as the Perseids in August. The outburst lasted a little over a day and was rich in bright meteors. "The night before, we had organised an observing effort for this one, but were all clouded out. Guess my surprise, when I arrived home late the next night and saw one bright Leonid after another. I sat down on my lawnchair and enjoyed the view in bright Moon- and city-light for the next hour and a half." - Peter Jenniskens Observations of the Leonids in 1995 and 1996 confirmed the enhanced rates. The parent comet 55P/Tempel-Tuttle was finally recovered on March 10, 1997, following an accurate prediction of its orbit, and passed perihelion on February 28, 1998.

The first increase of Leonid rates announcing the return of the comet was reported in 1994. Astronomer Peter Jenniskens was among the first to notice the high Leonid rates on November 18 that year, when the shower was as strong as the Perseids in August. The outburst lasted a little over a day and was rich in bright meteors. 1998 - the Leonid "Filament" first observed in 1994 soared during the night of November 16/17, 1998 , when observers all over the world were greeted by numerous fireballs and long lasting persistent trains. The peak of this component was over Europe. Leonid MAC deploys the FISTA and Electra aircraft to Okinawa, Japan. Participating researchers observe a second peak that is now thought to be a far encounter with the distorted 1899 dust trail.

, when observers all over the world were greeted by numerous fireballs and long lasting persistent trains. The peak of this component was over Europe. Leonid MAC deploys the FISTA and Electra aircraft to Okinawa, Japan. Participating researchers observe a second peak that is now thought to be a far encounter with the distorted 1899 dust trail. 1999 - The first close encounter with one of the narrow dust trails of comet 55P/Tempel-Tuttle in this return occurred in 1999, after new shower models had correctly predicted the timing of the meteor storm when Earth would pass dust ejected in 1899. Leonid MAC researchers have a prime view high above clouds just west of Greece, and return with spectacular footage of the storm.

occurred in 1999, after new shower models had correctly predicted the timing of the meteor storm when Earth would pass dust ejected in 1899. Leonid MAC researchers have a prime view high above clouds just west of Greece, and return with spectacular footage of the storm. 2000 - No storms expected, but rich outbursts confirm dust trail models . They are observed by Leonid MAC participants from ground locations in Florida, Arizona and Spain, and from a Cessna aircraft over Florida. A last quarter Moon makes observations very difficult.

. They are observed by Leonid MAC participants from ground locations in Florida, Arizona and Spain, and from a Cessna aircraft over Florida. A last quarter Moon makes observations very difficult. 2001 - While most predictions emphasize the 1866 dust trail encounter over Asia, Leonid MAC research concludes that the meteor storm over the continental USA will be excellent as well. All over the USA, a spectacular storm is viewed by millions of people in a Moon-less weekend night. Leonid MAC scientists have a prime view of this 1767 dust-trail encounter onboard the FISTA aircraft.

All over the USA, a spectacular storm is viewed by millions of people in a Moon-less weekend night. Leonid MAC scientists have a prime view of this 1767 dust-trail encounter onboard the FISTA aircraft. 2002 - Leonid MAC deploys from Spain to Nebraska and observes both meteor storms under excellent conditions. A near full Moon and unexpected faintness of meteors hampers observers on the ground.





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