The Geminids, arguably the most spectacular annual meteor shower of all takes place in December, with this year's peak occurring on the 13th. It is a superb shower, always reliable with many bright "shooting stars" and a peak zenithal hourly rate (ZHR) of over 100 meteors per hour, under ideal conditions. The Geminids are also known as the "Winter Fireworks" but they are not the only December meteors. Also worth looking out for are the Ursids. Although much less dramatic, with usually only about 10 meteors per hour, the Ursids have on several previous occasions shown significant bursts of intense meteor activity that may re-occur at anytime. This year's peak will occur on December 22nd.
The comet that sources and therefore responsible for the Ursid meteor shower is 8P/Tuttle (also known as Tuttle's Comet or Comet Tuttle). It has a period of 13.6 years and during the last perihelion on January 27, 2008 it was visible telescopically. The comet passed Earth at a distance of 0.25282 AU (37,821,000 km or 23,501,000 miles) on January 1, 2008 and anticipation was high that the 2007 and 2008 showers may produce much increased activity, but this was not to be. In the end only a small increase was noted.
The radiant for the Ursids meteors is located in the far northern constellation of Ursa Minor, "The Little Dipper". With a declination of +76 degrees, the Ursid radiant is circumpolar from most northern sites and conversely fails to rise from most southern sites. It is positioned just a few degrees northwest of Kochab (β UMi).
What to expect
The best two nights to look for the Ursids are on December 21/22 and 22/23. For this year's event, the Moon won't significantly interfere. The phase is waxing gibbous at time of peak activity and the Moon will set in the early hours of the morning. Normally the Ursids ZHR is about 10, although there have been at least two major outbursts in the past 70 years, in 1945 and 1986. During an outburst the ZHR can jump to at least 50, propelling the shower into the realms of some of the better annual meteor showers of the year.
When observing meteors, as always, wrap up warm (especially if its very cold) and look towards the general area of sky where the radiant is. Since the meteors can streak through the sky many degrees from the radiant, it's better not to look directly at it. To confirm an Ursid, trace back the meteor and it should go all the way back to the radiant.
Ursids 2012 Data Table
|Meteor shower name||Ursids|
|Radiant Constellation||Ursa Minor|
|Dates||17th December -> 26th December|
|Peak Date||22nd December|
|RA (J2000)||14hr 28m|
|ZHR||10 (occasionally up to 50)|