Meteor Activity Outlook for 4-10 December 2021

Daniel Bush captured this bright fireball on 22 September 2021 at 5:48 CDT (10:48 UT) from Albany, Missouri USA. More reports on this event can be found at: https://fireball.amsmeteors.org/members/imo_view/event/2021/5870 ©Daniel Bush

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 14th. There are also several minor sources 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. Much of the activity mentioned above can also be seen from the southern hemisphere. While the sporadic rates are not as strong as those seen from the north, they are stronger than the previous months and heading for a maximum in February. The warm, but short summer nights south of the equator make for some great viewing as long as the moon does not interfere.

During this period, the moon reaches its new phase on Saturday December 4. At that time the moon lies near the sun and is invisible at night. As the week progresses the waxing crescent moon will enter the evening sky but will set before the more active morning hours arrive. The estimated total hourly meteor rates for evening observers this week is near 4 as seen from mid-northern latitudes (45N) and 3 as seen from tropical southern locations (25S). For morning observers, the estimated total hourly rates should be near 25 as seen from mid-northern latitudes (45N) and 20 as seen from tropical southern locations (25S). 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. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brighter meteors will be visible from such locations.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning December 4/5. 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. I have also included charts of the sky that display the radiant positions for evening, midnight, and morning. The center of each chart is the sky directly overhead at the appropriate hour. These charts are oriented for facing south but can be used for any direction by rotating the charts to the desired direction. 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 sporadic. Meteor activity is not seen from radiants that are located far 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.

These sources of meteoric activity are expected to be active this week.

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The December Phoenicids (PHO) are a periodic shower that rarely produces noticeable activity. The only impressive display produced so far by this shower occurred in 1956 when ZHR’s were near 100. The normal rage for these meteors is from November 28 through December 9 with a peak on December 5. The radiant at maximum is located at 01:12 (018) -53. This position lies in southern Phoenix, 5 degrees south of the 3rd magnitude star known as beta Phoenicis. For those viewing from the northern tropics southward, this position also lies 7 degrees northwest of the bright 1st magnitude star known as Achernar (alpha Eridani). This area of the sky is best placed as soon as evening twilight ends. These meteors are best seen from the southern hemisphere where the radiant lies much higher in the sky. For those viewing from the northern hemisphere, only those in the northern tropics have any real chance of seeing activity from this source. At only 12 km/sec. the Phoenicids produce extremely slow meteors.

Now that the activity from particles produced by comet 2P/Encke have ceased encountering the Earth, the Taurid showers for 2021 are over and we resume reporting activity from the Anthelion (ANT) radiant. This is not a true radiant but rather activity caused by the Earth’s motion through space. As the Earth revolves around the sun it encounters particles orbiting in a pro-grade motion that are approaching their perihelion point. They all appear to be radiating from an area near the opposition point of the sun, hence the name Anthelion. These were once recorded as separate showers throughout the year, but it is now suggested to bin them into a category separate from true showers and sporadics. This radiant is a very large oval some thirty degrees wide by fifteen degrees high. Activity from this radiant can appear from more than one constellation. The position listed here is for the center of the radiant which is currently located at 05:40 (085) +23. This position lies in eastern Taurus, 3 degrees northeast of the 3rd magnitude star known as Tianguan (zeta Tauri). Since the radiant is so large, Anthelion activity may also appear from southeastern Auriga, Gemini, and northeastern Orion as well as eastern Taurus. This radiant is best placed near midnight local standard time (LST) when it lies on the meridian and is highest in the sky. Rates at this time should be near 2 per hour as seen from the northern hemisphere and 1 per hour as seen from south of the equator. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.

The November Orionids (NOO) are active from November 13 through December 12, with maximum activity occurring on November 30^th. The radiant is currently located at 06:24 (096) +16. This area of the sky lies on the in northeastern Orion, 3 degrees northeast of the 4th magnitude star known as xi Orionis. This radiant is best placed in the sky near 0100 LST, when it lies highest above the horizon. Rates should be near 2 per hour as seen from the Northern Hemisphere and 1 per hour as seen from south of the equator. With an entry velocity of 42 km/sec., most activity from this radiant would be of medium speed.

The Monocerotids (MON) are active from November 23 through December 24 with the peak activity occurring on December 11th. The radiant is currently located at 06:32 (098) +09. This position lies in western Monoceros, 8 degrees northeast of the 1st magnitude orange star known as Betelgeuse (alpha Orionis). This position is only 6 degrees south of the radiant of the November Orionids so care must be taken to distinguish between the two. Current rates should be 1 per hour as seen from the Northern Hemisphere and less than 1 as seen from south of the equator. Rates at maximum may reach 2 per hour. The Monocerotids are best seen near 0100 LST when the radiant lies highest above the horizon. At 42 km/sec. the Monocerotids produce mostly meteors of medium velocity.

The Geminids (GEM) have recently been found to be active from November 19 through December 24. The early Geminids are sometimes referred to as the theta Aurigids (THA). The radiant is currently located near 06:52 (103) +33. This position lies in northern Gemini, 1 degree south of the 4th magnitude star known as theta Geminorum. Rates this weekend should be near 3 per hour as seen from the Northern Hemisphere and near 1 as seen from south of the equator. This radiant is best placed in the sky near 0200 LST, when it lies highest above the horizon. At 33 km/sec. the Geminids produce mostly meteors of medium velocity.

The Puppid-Velids (PUP) are a vast complex of weak radiants located in the constellations of Puppis and Vela. Visual plots and photographic studies have revealed many radiants in this area during November and December. The combined strength of these radiants can produce a ZHR of 10. Actual hourly rates will be much less unless you happen to be observing from the deep Southern Hemisphere. Activity from this source begins around December 1st. The center of this activity is currently located at 08:08 (122) -45. This position lies in western Vela, 2 degrees northeast of the 2nd magnitude star known as gamma Velorum. Peak rates occur near December 7. These meteors are best seen near 0300 LST when the radiant lies highest above the horizon in a dark sky. Observers located in the Southern Hemisphere have an advantage viewing this shower as the radiant will rise higher into their sky allowing more activity to be seen. Since the radiant lies low in the south for most northern hemisphere observers, meteors seen from north of the equator tend to be long in length and long-lasting. At 40 km/sec. the Puppid-Velids produce meteors of average velocity. Note: these are also listed as the “e Velids” from several sources.

The sigma Hydrids (HYD) are active from a radiant located at 08:08 (122) +03. This area of the sky is located in eastern Canis Minor, 6 degrees southeast of the bright zero magnitude star known as Procyon (alpha Canis Minoris). Current rates should be near 3 per hour no matter your location. These meteors are best seen near 0300 LST, when it lies highest above the horizon in a dark sky. With an entry velocity of 59 km/sec., the average sigma Hydrid meteor would be of swift velocity.

The December Leonis Minorids (DLM) are a shower of long duration active from December 1^st all the way through February 10th. Maximum occurs near December 19th when rates may reach 3 an hour. During this period, I would expect hourly rates of 1 from a radiant located at 09:56 (149) +37. This position lies in central Leo Minor, 2 degrees northwest of the faint star known as 21 Leonis Minoris. These meteors are best seen near 0400 LST when the radiant lies highest above the horizon. At 63 km/sec. the December Leonis Minorids produce mostly swift meteors.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately 11 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 3 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 8 per hour as seen from rural observing sites and 2 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.