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The annual Draconids meteor shower peaks this year on the night of October 8th. Although normally a feeble shower it does have a history of spectacular outbursts and for that reason it's certainly worth looking out for. The best place and time to observe is from Northern locations during the evenings of October 8th and 9th. This year's event also benefits as the waning crescent Moon won't significantly interfere.

The Zenithal Hourly Rate (ZHR) of a meteor shower is the number of meteors a single observer would see in one hour under a clear dark sky if the radiant of the shower was at the zenith. Usually the ZHR of the Draconids is extremely low at only 1 or 2 meteors, even below the accepted sporadic rate. However the shower can burst into life and on occasions rates as high as 6,000 meteors per hour have been seen over short periods. When the Dragon roars its a spectacular sight!

Comet 21P/Giacobini Zinner the parent body of the Draconids (credit - NASA)

Parent Comet

The dust and debris left behind from periodic comet 21P/Giacobini-Zinner as it orbits the Sun are the source powering the Draconids meteor shower. The shower has also been unofficially known as the Giacobinids. Comet Giacobini-Zinner is a short period comet with an orbital period of just 6.6 years. It was discovered on the December 20, 1900 in Nice by French astronomer Michel Giacobini and was subsequently lost and then re-discovered two orbits later on the October 23, 1913 by German astronomer Ernst Zinner at the Remeis Observatory in Bamberg, Bavaria.

During apparitions, Giacobini-Zinner can reach 8th magnitude in brightness although it's known to flare. For example in 1946 the comet brightened significantly to attain 5th magnitude and naked eye brightness. It will next be in our vicinity near perihelion on September 15th, 2018.

Previous observations

Historically, great Draconids storms have occurred in 1933 and 1946. In 1933 observers recorded an hourly rate of 6,000 meteors over a short period. Most meteors were slow moving and faint (between 3rd and 5th magnitude). Likewise a similar storm occurred in 1946 when many thousands of meteors were seen. On both occasions the activity was short, lasting only about 3 hours in total. Lesser but noteworthy outbursts occurred in 1952, 1985, and 1998, with lower rates but still of the order of hundreds of meteors an hour. The last bursts of activity occurred in 2011 where European observers saw over 600 meteors per hour despite an almost full Moon interfering and in 2012 where radar observations detected up to 1000 meteors per hour.

Radiant

The Draconids radiant is located in the faint far northern constellation of Draco the Dragon, not far from the famous constellation of Ursa Major "the Great Bear" and the bright star Vega (α Lyr - mag. 0.0). To locate the correct region of sky, look to the northwest in early evening. With a radiant of +54 degrees this is essentially a Northern Hemisphere shower.

Location of Draconids radiant - looking northwest early evening from northern latitudes in October (credit:- stellarium)

For those located at southern latitudes the Draconids radiant is either very low down or never even climbs above the horizon. This considerably reduces the number of meteors likely to be seen, although it may be possible to see a meteor coming up from the northern horizon.

To spot as many Draconids as possible the best advice is to find a dark observing with an unobstructed view of the sky. Then scan a large area of sky surrounding the radiant but not directly at the radiant. The reason is that even though the meteors originate from the radiant they can appear many tens of degrees from it.

Draconids Radiant and Star Chart (credit:- freestarcharts)

Draconids Radiant and Star Chart - pdf format (credit:- freestarcharts)

What's in store for 2015?

Nobody is predicting anything spectacular for 2015 but you can never be certain with this shower. There is always uncertainty associated with the Draconids, more likely a complete washout but a spectacular storm may happen. It's therefore worth watching on the nights of October 8th and 9th as you may just witness a spectacular celestial event.

Draconids Data Table 2015

Meteor shower nameDraconids
Meteor shower abbreviationDRA
Radiant constellationDraco
ActivityOctober 6th -> October 10th
Peak DateOctober 8th
RA (J2000)17hr 28m
DEC (J2000)+54d
Speed (km/s)20
ZHR Variable: 1 to 2 (normal) 6000 (storm)
RatingMedium brightness
Parent body21P/Giacobini-Zinner
NotesAlso known as Giacobinids or October Draconids

Comet 21P/Giacobini-Zinner Data Table (at epoch March 13, 2013)

Name21P/Giacobini-Zinner
TypeComet
ClassificationJupiter-family comet (NEO)
DiscovererMichel Giacobini and Ernst Zinner
Discovery dateDecember 20th, 1900
Aphelion (AU)6.00119
Perihelion (AU)1.03051
Semi-major axis (AU) 3.51585
Eccentricity0.70690
Orbital period (years)6.59271
Inclination (degrees) 31.8108
Longitude of ascending node (degrees)195.394
Last perihelion February 11th, 2012
Next perihelion September 15th, 2018