Flashback 1933: The Great Meteor Shower of Draco The Dragon (Draconids or Giacobinids)
From Wikipedia, the free encyclopedia
The October Draconids, in the past also unofficially known as the Giacobinids, are a meteor shower whose parent body is the periodiccomet 21P/Giacobini-Zinner. They are named after the constellationDraco, where they seemingly come from. Almost all meteors which fall towards Earth ablate long before reaching its surface. The Draconids are best viewed after sunset in an area with a clear dark sky.
The 1933 and 1946 Draconids had Zenithal Hourly Rates of thousands of meteors visible per hour, among the most impressive meteor storms of the 20th century. Rare outbursts in activity can occur when the Earth travels through a denser part of the cometary debris stream; for example, in 1998, rates suddenly spiked and spiked again (less spectacularly) in 2005. A Draconid meteor outburst occurred as expected on 2011 October 8, though a waxing gibbous Moon reduced the number of meteors observed visually. During the 2012 shower radar observations detected up to 1000 meteors per hour. The 2012 outburst may have been caused by the narrow trail of dust and debris left behind by the parent comet in 1959.
- Flashback 1933: The Great Meteor Shower of Draco The Dragon
The discovery of this meteor shower resulted from predictions by several astronomers that the periodic comet 21P/Giacobini-Zinner might produce a radiant in early October. The first to make such a prediction was M. Davidson, who, in 1915, examined the periodic comets observed since 1892 to isolate any that might be capable of producing meteor showers. One of the comets which met the established criteria was 21P/Giacobini-Zinner.
The 1933 Return
Comet 21P/Giacobini-Zinner passed perihelion on July 15, 1933, and, at the time of the predicted maximum of October 9, Earth crossed the area of the comet’s descending node just 80 days after the comet. Astronomers were not prepared for what was in store for them, but, as evening twilight fell over Europe, observers noted the beginnings of something unusual. Within just a couple of hours the number of Draconids skyrocketed, and, at 20:00 UT, one of the best displays of the 20th century was in progress. Some of the more impressive statistics follow:
* From Ireland, W. Ellison (Armagh Observatory) reported that meteors fell as frequently as snowflakes and he gave the radiant as α=26°, δ=+55°. W. Milligan (near Omagh) saw thousands, including 100 during one 5-second interval. The radiant was α=264.5°, δ=+54.5°.
* At Birchircara, Malta, R. Forbes-Bentley observed over 22,500 meteors in just a few hours and estimated the peak rate hit 480 per minute at 20:15 UT. The meteors were described as mostly faint with only 5% reaching first magnitude. The radiant was estimated as α=262.5°, δ=+55°.
* In Russia, N. S. Sytinskaja (Leningrad) collected numerous observations between 18:00 and 22:00. At maximum, rates reached 100 per minute at Leningrad, 300 per minute at Pulkovo and 200 per minute at Odessa.
* From Spain, P. M. Ryves (Zaragoza) estimated a maximum rate of 100 per minute and an average radiant of α=266°, δ=+53.5°. He said the meteors were generally faint with the “great majority of the meteors being 3rd to 5th mag.”
As can be gathered from these reports (and many others not included here), the shower’s maximum rate reached 100 per minute, or about 6000 per hour, around 20:15 UT on October 9. The meteors were slow, generally faint and were usually yellow.
Following the 1933 appearance, the Draconids again fell to nonexistence. The comet’s next perihelion date was February 17, 1940, and there were numerous predictions of a possible strong return in October 1939. However, Earth crossed the comet’s orbit 136 days ahead of the comet which meant bad news for meteor enthusiasts, as no storm—or even a small shower—appeared.
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