The annual Draconids meteor shower peaks this year on the nights of October 7th and October 8th. Although it's normally a feeble shower it does have a history of spectacular outbursts and therefore worth looking out for. This year's shower also benefits as the thin crescent Moon won't interfere.
The Zenithal Hourly Rate (ZHR) is the number of meteors a single observer would see in one hour under a clear, dark sky (limiting apparent magnitude of 6.5) if the radiant of the shower were at the zenith. Usually the ZHR (Zenithal Hourly Rate) for the Draconids is extremely low at only 1 or 2 meteors. In reality this will almost never happen and therefore the number of meteors observed is much less than the quoted value. However, historically great storms have occasionally occurred with recorded hourly rates as high as 6,000 meteors over a short period.
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 flair, for example in 1946, when 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.
The radiant is located in the faint far northern constellation of Draco the Dragon, not far from the famous constellations of Ursa Minor, "the Little Bear" and Ursa Major, "the Great Bear". To locate the correct region of sky, look to the northwestern part of the sky. With a radiant of 54 degrees north, this is essentially a northern hemisphere shower.
For those located in the southern hemisphere, 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 spot a meteor coming up from the northern horizon.
To spot as many Draconids as possible the best advice is the 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 usually appear many tens of degrees in the sky from it.
The star chart below shows the location of the Draconids meteor shower radiant.
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 burst of activity occurred recently in 2011 where European observers saw over 600 meteors per hour despite an almost full Moon interfering.
What's in store for 2013?
Nobody is predicting anything spectacular for 2013 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 7th and 8th as you may just witness a spectacular celestial event.
Draconids Data Table 2013
|Meteor shower name||Draconids|
|Meteor shower abbreviation||DRA|
|Activity||October 6th -> October 10th|
|Peak Date||October 7th -> October 8th|
|RA (J2000)||17hr 28m|
|ZHR||Variable: 1 to 2 (normal) 6000 (storm)|
|Notes||Also known as Giacobinids or October Draconids|
Comet 21P/Giacobini-Zinner Data Table (at epoch March 13, 2013)
|Classification||Jupiter-family comet (NEO)|
|Discoverer||Michel Giacobini and Ernst Zinner|
|Discovery date||December 20th, 1900|
|Semi-major axis (AU)||3.51585|
|Orbital period (years)||6.59271|
|Longitude of ascending node (degrees)||195.394|
|Last perihelion||February 11th, 2012|
|Next perihelion||September 15th, 2018|