The annual Orionids meteor shower peaks this year on October 21st and the prospects are excellent as the Moon will not interfere. Generally regarded as a strong shower, the Orionids or Orionid meteor shower is active between October 2nd and November 7th, although most activity is at peak date or a few days before or after it. In the past, rates of up to 70 per hour have been observed but normally the shower is not so active; a figure between 20 and 25 is more the normal at the moment.
The Orionids parent comet is the most famous of all, Halley's Comet (1P/Halley). There are two annual meteor showers associated with Halley's Comet, the Eta Aquariids shower that occurs in May and the then the Orionids. Of the two the Orionids is far the more prolific.
Although Halley is now in the outer solar system and will not return close to Earth until 2061, it's worth remembering that Orionids meteors stem from particles leftover from Halley's Comet apparitions every 76 years. Every observed Orionid is actually a small part of the famous comet streaking through and subsequently burning up in the Earth's atmosphere.
The radiant of the Orionids is located in the northeastern part of the constellation Orion, not far from the Gemini border. Since Orion straddles the celestial equator, the Orionids are one of the few annual showers that are well placed for observation from most locations on Earth (exception the polar regions).
What to expect in 2014?
This year promises to be excellent with the 10% illuminated waning crescent Moon not interfering. The best time to observe is between October 20th and 22nd. Although no major burst of activity is expected the shower is usually reliable with bright meteors and should put on a superb show with up to 25 meteors per hour visible.
The Orionids are fast meteors that they hit the atmosphere at very high speeds of about 235,000 km/hour (145,000 miles/hour). To the eye they will appear to streak across the sky. As with all annual meteors showers, it's best not to look directly at the radiant itself as the meteors can appear many degrees from it.
Orionids Data Table 2014
|Meteor shower name||Orionids|
|Meteor shower abbreviation||ORI|
|Activity||October 2nd -> November 7th|
|Peak Date||October 21st|
|RA (J2000)||6hr 20m|
|ZHR||20 to 25 (can vary between 20 and 70)|
|Notes||Most prolific meteor shower associated with Halley's Comet|
Comet 1P/Halley Data Table (at epoch February 17th, 1994)
|Classification||Halley-type comet (NEO)|
|Discoverer||Prehistoric, Edmond Halley first recognised the periodicity|
|Semi-major axis (AU)||17.8341|
|Orbital period (years)||75.3175|
|Longitude of ascending node (degrees)||58.4201|
|Last perihelion||February 9th, 1986|
|Next perihelion||July 28th, 2061|
|Notes||Halley's comet, the most famous of all comets|