Meteor Activity Outlook for November 22-28, 2008

As seen from the northern hemisphere, meteor
rates continue to be strong in November. While no major showers are active this
month, the two Taurid radiants plus the Leonids keep the skies active. The
addition of strong sporadic rates make November one of the better months to view
meteor activity from north of the equator. Skies are fairly quiet as seen from
the southern hemisphere this month. Activity from the three showers mentioned
above may be seen from south of the equator, but the sporadic rates are much
lower than those seen in the northern hemisphere.

During this period the moon reaches its new
phase on Thursday November 27th. At this time the moon will rise and set with the
sun and will not be visible at night. This weekend the waning crescent moon
will rise during the late morning hours and will not be too bothersome. The
estimated total hourly rates for evening observers this week is near five for
those located in the mid-northern hemisphere (45 N) and two for those viewing from
the mid-southern hemisphere (45 S). For morning observers the estimated total
hourly rates should be near twenty 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. Morning rates are slightly decreased due to moonlight.

The radiant positions and rates listed below are exact
for Saturday night/Sunday morning November 22/23. 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:

At this time of year debris from comet 2P/Encke produces a double radiant
very close to the position of the antihelion radiant. From now through the
end of November, it is impossible to resolve the antihelion meteors from
those produced by comet 2P/Encke. Therefore we suggest that observers simply
classify meteors from this area as either north or south Taurids.

The center of the large Northern Taurid (NTA) radiant is now centered at
04:32 (068) +24. This position lies in central Taurus, eight degrees north of
the orange first magnitude star Aldebaran (Alpha Tauri). The center of the large
Southern Taurid (STA) radiant lies at 04:36 (069) +17. This position also
lies in central Taurus, only one degree north of Aldebaran. The two radiants are
separated by approximately seven degrees. Since they have the same right ascension
(celestial longitude), it is difficult to distinguish meteors that move north or
south out of the radiants. It is less difficult to distinguish those meteors
traveling east or west. These radiants are best placed near the meridian at 0100
LST (Local Standard Time). At 29 and 27 km/sec., the average Taurid meteor travels
slowly through the skies.

Sirko Molau’s new studies of video radiants has revealed that the Northern Taurid’s
reach two plateaus of activity with the first occurring on October 20th. The
moon subdued this activity so it was most likely not noticed. The secondary peak was
predicted to occur near November 13th and was severely hampered by a bright moon.
The same study has revealed that the Southern Taurids may have peaked near
October 11 and that the activity for this shower will remain fairly constant through
the first week of November. After that rates will dwindle until these meteors disappear
near the end of November.

Sirko Molau’s study of video radiants has shown that activity from northern Orion
begins to appear on November 18 from a radiant located at 5:44 (086) +15. This
position lies seven degrees northwest of the orange first magnitude variable star
Betelgeuse (Alpha Orionis). Current rates should be near one shower member
per hour. These meteors are best seen near 0200 LST when the radiant culminates
on the meridian. Maximum activity occurs on the 28th when several meteors per hour
should be visible. At 45 km/sec. the November Orionids (NOO) produce meteors
of medium-swift velocity. This shower has a very similar radiant position with the
better known and much more active Orionids (of October and early November). Last
year I called these the Lambda Orionids, not knowing the IAU had already listed a
designation for this shower.

Surprisingly, Sirko’s most recent study of radiant activity using video methods
has shown that the first traces of the Geminids (GEM) begin to appear on
November 23rd. At this time the radiant is located at 06:04 (091) +34. This position
lies in southeastern Auriga, three degrees southeast of the third magnitude star
Theta Aurigae. These meteors are best seen near 0200 LST when the radiant lies
highest above the horizon in a dark sky. Since we are a full three weeks before
maximum, rates would be low, most likely less than one per hour. At 35 km/sec.
the Geminids produce mostly medium speed meteors.

The first traces of the Sigma Hydrids (HYD) begin to appear on November
22nd. At this time the radiant is located at 07:28 (112) +07. This position lies
in central Canis Minor, two degrees west of the zero magnitude star Procyon
(Alpha Canis Minoris). These meteors are best seen near 0400 LST
when the radiant lies highest above the horizon in a dark sky. At 60 km/sec.
the Alpha Monocerotids produce mostly swift meteors.

The Alpha Monocerotids (AMO) reach maximum activity on November 21st with
normally low rates of one or two shower members per hour. This shower has
produced outbursts in the past but none are expected for many years to come.
The radiant is located at 07:48 (117) +01. This position lies in southeastern
Canis Minor, five degrees southeast of the zero magnitude star
Procyon (Alpha Canis Minoris). These meteors are also best seen near 0400 LST
when the radiant lies highest above the horizon in a dark sky. At 65 km/sec.
the Alpha Monocerotids produce mostly swift meteors.

The Leonids (LEO) peaked over Europe on the morning of November 17th. Rates
are now falling and the last members of the Leonid shower will be seen up to November
28th. Hourly rates will be near one this weekend and then less than one the remainder
of the week. The radiant is currently located at 10:20 (155) +19. This position lies
in western Leo, only one degree southwest of the famous orange double star Algeiba
(Gamma Leonis). At 71km/sec., the average Leo is swift with a high percentage of
trains. The radiant is most favorably located during the last dark hour before the
onset of morning twilight.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately
fourteen Sporadic meteors per hour during the last hour before dawn as seen from
rural observing sites. Evening rates would be near four per hour. As seen from the
mid-southern hemisphere (45S), morning rates would be near five per hour as seen
from rural observing sites and one per hour during the evening hours. Locations
between these two extremes would see activity between the listed figures. Morning
rates are slightly reduced during this period due to moonlight.

The table below presents a summary of the expected activity this week. Rates and
positions are exact for Saturday night/Sunday morning but may be used all week.