Meteor Activity Outlook for December 21-27, 2007

No matter where you live, the first half of December provides some of the best meteor activity of the year. In the northern hemisphere the sporadic rates are still strong plus you can also count on strong activity from the Geminids, which peak on December 14. There are also several minor radiants that add a few meteors each hour. All of these centers of activity are located high in the sky during the early morning hours this time of year. The night of December 13/14 is no doubt the best night of the year to view meteor activity. The moon is favorable during this entire period. After the 15th, the shower activity suddenly wanes and a great majority of the activity seen is sporadic. Approaching Christmas the moon become a major factor and ruins the maximum of the Ursid shower.

As seen from the southern hemisphere the sporadic rates are increasing toward a January maximum. Shower rates are also good but the Geminids suffer a bit from the lower elevation seen from southern locations. Still with the warmer weather now occurring south of the equator, December is a great time to view celestial fireworks.

During this period the moon reaches its full phase on Monday December 24. The moon will remain a major factor during this entire period obscuring all but the brightest meteors. The sources of meteors listed below are active during this period but will be difficult to observe this week due to the lunar glare. If your sky is transparent and the limiting magnitude exceeds +5.0, then you may be able to achieve some success. The estimated total hourly rates for evening observers this week is two from the northern hemisphere and one from south of the equator. For morning observers the estimated total hourly rates should be near seven from the northern hemisphere and four from the southern hemisphere. These rates assume that you are watching from rural areas away from all sources of light pollution. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Rates are reduced this week due to intense moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning December 21/22. These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies at the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.

The full descriptions of each active meteor shower will continue next week when the moon becomes less of a nuisance to observers. It should be noted that the Ursids may produce a short outburst near 21UT on the 22nd. This timing favors Europe, Asia, and the northern polar regions.