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.