The Alpha Capricornids is a meteor shower that lasts for about 6 weeks from July 3rd to August 15th, with this year's peak occurring at the end of July. Despite being an infrequent shower with rarely more than 5 meteors per hour visible, it's worth watching out for the Alpha Capricornids as the meteors are bright and often include spectacular colourful fireballs.
Unlike some of the other annual meteor showers, Alpha Capricornids don't have a well-defined peak. Instead, maximum activity is spread over a "plateau like" period which varies from year to year. This year, July 30th and 31st are predicted to be the days of peak activity. A waning crescent Moon between 45% and 30% illuminated is visible at this time, but should not significantly interfere.
Discovery and Parent Body
The meteor shower was discovered by Hungarian astronomer Miklos von Konkoly-Thege in 1871. It was not until 2009 that Peter Jenniskens and Jeremie Vaubaillon identified the parent body as asteroid 2002 EX12. This object was subsequently identified as a comet and renamed as 169P/NEAT.
It's believed that the bulk of the cometary dust particles will not cross Earth's orbit for another 300 years and as a result the shower could be a major calendar event from 2220 to 2420 AD.
The shower radiant is located in Capricornus, close to the constellation boundary with Aquila and Aquarius. The meteors are well seen from all over the globe, with the tropics being the preferred location. Southern temperate latitudes are slightly better placed for observation than their northern counterparts. Just after midnight the radiant is position towards the south for northern hemisphere observers, overhead from the tropics and more towards the north for those located further south.
The best time of night to observe the meteor shower is around midnight or during the early hours of the morning. The Alpha Capricornids are noticeably slow moving meteors (velocity 23 km/s) and as previously mentioned, often produce brilliant colourful fireballs that leave a trail of dust and debris as they disintegrate in the Earth's atmosphere.
As with all meteor showers the meteor trails often streak across the sky quite a distance from the actual radiant point, in many cases in excess of 30 degrees and therefore can effectively appear anywhere in the sky. It's therefore a good idea not to look directly at the radiant itself, but scan a large area of the sky around it.
Alpha Capricornids Data Table 2013
|Meteor shower name||Alpha Capricornids|
|Activity||July 3rd -> August 15th|
|Peak Date||July 30th / 31st|
|RA (J2000)||20hr 28m|
|Notes||Produces a few slow moving but relatively bright meteors including some fireballs|
Comet 169P/NEAT Data Table (at epoch May 15th, 2007)
|Classification||Jupiter-family comet (NEO)|
|Discoverer||NEAT (Near-Earth Asteroid Tracking)|
|Discovery date||March 15th, 2002|
|Aphelion distance (AU)||4.60176|
|Perihelion distance (AU)||0.60660|
|Orbital period (years)||4.20266|
|Last perihelion||November 30th, 2009|
|Next perihelion||February 12th, 2014|
|Notes||Previously known as asteroid 2002 EX12|