Meteor Activity Outlook for December 28, 2007-January 3, 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 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 last
quarter phase on Monday December 31. At this time the moon will be located ninety
degrees west of the sun and will rise near midnight local standard time (LST). This
weekend the waning gibbous moon will be quite bothersome unless your sky is
transparent. Toward the end of this period the waning crescent moon will become
less of a factor with each passing morning. The estimated total hourly rates for evening observers
this week is near three for those located in the mid-northern hemisphere (45 N) and
two for observers from the mid-southern hemisphere (45 S). For morning observers
the estimated total hourly rates should be near fourteen for those located in the
mid-northern hemisphere (45 N) and ten for those viewing from the mid-southern
hemisphere (45 S). 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. Morning rates are reduced by moonlight.

The radiant positions and rates listed below are exact
for Saturday night/Sunday morning December 29/30. 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 following showers are expected to be active this week:

The Earth has now passed the stream of particles produced by comet 2P/Encke,
which gives us the Taurid meteors each autumn. As we enter the month of December
we again recognize the ever present Antihelion (ANT) radiant. This large,
diffuse radiant is now centered at 07:24 (111) +21. This position lies in central
Gemini near the third magnitude star Delta Geminorum. This area
of the sky is best placed on the meridian near 0100 local standard time (LST). One
can expect to see approximately two shower members per hour as seen from the
northern hemisphere and one per hour from south of the equator. At 30km/sec., the
average Antihelion meteor travels slowly through the skies.

Sirko Molau’s study of video radiants has revealed activity during the
period January 3-9, from an area in western Hydra. Maximum occurs on January 4
with the radiant located at 08:32 (128) -13. This position lies fifteen degrees
southwest of the second magnitude star (Alpha Hydrae (AHY)). This radiant
is best placed near 0200 LST when it lies on the meridian and is highest in the
sky. Rates are most likely less than one shower member per hour no matter
your observing location. At 39km/sec., the average meteor from this radiant
would be of average velocity.

Sirko Molau’s study of video radiants has also revealed activity during the
period January 1-6, from an area in western Leo. Maximum occurs on January 3 with
the radiant located at 09:44 (146) +25. This position lies very close to the third
magnitude star (Epsilon Leonis (ELE)). This radiant
is best placed near 0300 LST when it lies on the meridian and is highest in the
sky. Rates are most likely less than one shower member per hour no matter your
observing location. At 55km/sec., the average meteor from this radiant would be
swift.

The Coma Berenicids (COM) are active from a radiant located at 12:20 (185)
+21. This area of the sky is located in western Coma Berenices, eight degrees
northeast of the second magnitude star Denebola (Beta Leonis). This radiant is
probably responsible for the many reports of activity in Leo during
the month of December. Current rates would be near one shower member per hour.
These meteors are best seen near 0600 local standard time when the radiant lies
highest above the horizon. At 65 km/sec. the Coma Berenicids will usually produce
meteors of swift velocity.

The Quadrantids (QUA) reach a ZHR of one on New Year’s day. Stragglers from
this shower may be detected as early as December 28. Shower activity will lie far
below the sporadic rates up to January 3. On the 3rd, rates begin to increase
rapidly reaching maximum activity near 0640 UT on January 4. This timing is good
for the Northern Atlantic region including extreme western Europe and eastern
North America. The exact maximum is difficult to catch under perfect conditions
where the shower peaks with the radiant located high in the sky. Most observers
will do well seeing rates of fifty Quadrantids per hour. Most of Europe and North
America will see maximum rates of less than fifty per hour. From high northern latitudes
some Quadrantid activity may be seen during the evening hours. A few Quadrantids
may be seen from the equator and low southern latitudes during the small window
of time between the rise of the radiant and the start of morning twilight. At higher
southern latitudes the radiant does not rise until the sky is too bright so no
Quadrantid activity is visible south of approximately 30 degrees south latitude.
On January 4th the radiant is located at 15:20 (230) +49. This area of the sky is
located in an empty portion of northeastern Bootes some twenty degrees east of the
second magnitude star Alkaid (Eta Ursae Majoris). The nearest bright star is third
magnitude Beta Bootis, lying eight degrees to the southwest of the Quadrantid radiant.
On the morning of January 5, the rates have dropped back below the sporadic background.
The ZHR is back down to one on January 6 and all traces of the shower disappear
by January 13. At 49 km/sec. the Quadrantids produce meteors of average to swift
velocity. This shower is also known as the Bootids.

Sporadic rates are now slowly falling for observers in the northern
hemisphere and rising for those located south of the equator. One would expect to
see approximately ten random meteors during the last hour before dawn from rural
observing sites in the mid-northern hemisphere (45 N). During the first dark hour
after the end of evening twilight, perhaps three random meteors can be seen per
hour. As seen from the mid-southern hemisphere (45 S) late morning rates would now
be near eight per hour. During the first dark hour after the end of evening
twilight, perhaps two random meteors can be seen per hour. Morning rates are
reduced due to moonlight.