Meteor Activity Outlook for December 13-19, 2008

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 13. 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.

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 last quarter
phase on Friday December 19th. At this time the moon will rise near midnight local
standard time (LST) and will be in the sky the remainder of the morning. This
weekend and next week the waning gibbous moon will be in the sky most of the night
making it difficult to observe any activity. The estimated total hourly rates for evening
observers this week is near five for those located in the mid-northern hemisphere
(45 N) and three for those viewing from the mid-southern hemisphere (45 S). For
morning observers the estimated total hourly rates should be near twenty five for those
located in the mid-northern hemisphere (45 N) and ten for those viewing from
the mid-southern hemisphere (45 S). Locations between these two extremes would see
activity between the listed figures. 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 due to the bright moonlight.

The radiant positions and rates listed below are exact
for Saturday night/Sunday morning December 13/14. 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.

The following showers are expected to be active this week: