بارش شهابی جبّاری یکی از بارشهای شهابی سالانهاست که کانون بارش آن در صورت فلکی جبار به نظر میرسد. بارش شهابی جباری بارش خیلی مشهوری نیست امّا با این وجود جالب توجّهاست. این بارش معمولاً هر سال از حدود روز ۱۰ ماهمهر تا حدود روز ۱۶ ماهآبان فعّال است و در حدود روز ۲۹ ماه مهر به اوج میرسد. سرعت میانگین شهابهای این بارش نسبت به کره زمین در اوقات اوج این بارش معمولاً حدود ۶۶٫۲ کیلومتر بر ثانیهاست که نسبتاً زیاد بهشمار میآید امّا شهابهای این بارش چندان روشن نیستند و در عوض از خود خاکستر بیش تری بر جا میگذارند. نرخ ساعتی سرسویی اوج این بارش معمولاً حدود ۳۰ است که البتّه نرخ ساعتی سرسویی اوج هر بارش شهابی تغییر میکند.
The Orionid meteor shower, usually shortened to the Orionids, is the most prolificmeteor shower associated with Halley's Comet. The Orionids are so-called because the point they appear to come from, called the radiant, lies in the constellationOrion, but they can be seen over a large area of the sky. Orionids are an annual meteor shower which last approximately one week in late October. In some years, meteors may occur at rates of 50–70 per hour.
Meteor showers first designated "shooting stars" were connected to comets in the 1800s. E.C. Herrick made an observation in 1839 and 1840 about the activity present in the October night skies. A. S. Herschel produced the first documented record that gave accurate forecasts for the next meteor shower. The Orionid meteor shower is produced by the well known Halley's Comet, which was named after the astronomerEdmund Halley and last passed through the inner solar system in 1986 on its 75- to 76-year orbit. When the comet passes through the solar system, the sun sublimates some of the ice, allowing rock particles to break away from the comet. These particles continue on the comet's trajectory and appear as meteors ("falling stars") when they pass through Earth's upper atmosphere. Halley's comet is also responsible for creating the Eta Aquariids, which occur each May.
* This meteor shower may give double peaks as well as plateaus, and time periods of flat maxima lasting several days.
Meteor shower and location
Map of the night sky showing the constellation Orion and Betelgeuse and a portion of the Gemini constellation
The radiant of the Orionids is located between the constellations Orion and Gemini (in the south-eastern sky before dawn, as viewed from mid-northern latitudes. The most active time of the meteor shower was stated by Telegraph.co.uk to be in the early morning of October 21, 2009 6 a.m.Eastern Standard Time in the United States or 11 a.m. in the United Kingdom. Universe Today reported that the meteor shower arrived at 140,000 miles (230,000 km) per hour on the morning of the 21 when showing was predicted to be at its height, however compared to previous showers in years past, the trail of 2009 appeared narrower without branching out. Observers observing the small meteor "Halleyids" at Alabama's Space Flight Center saw streaks radiating in all directions with the naked eye.