No matter where you live, the first half of December provides some of the best
meteor activity of the year. This activity will be tempered by a bright moon
during the first week of the month. The next two weeks are moon-free and offer
the meteor observer ample opportunities to view some celestial fireworks. 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. 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 last quarter phase on Thursday December
6th. At this time the moon is located ninety degrees west of the sun and rises
near 2300 (11pm) local standard time (LST). This weekend the waning gibbous moon
will rise during the early evening hours and will effectively spoil the sky the
remainder of the night with its intense lunar glare. The estimated total hourly
meteor rates for evening observers this week is near four for observers located
at mid-northern latitudes and three for observers in mid-southern latitudes. For
morning observers the estimated total hourly rates should be near twelve from
the mid-northern hemisphere and seven from the mid-southern hemisphere. 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 during this period due to moonlight.
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 1/2. 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.
Details of each active shower will return next week when the observing
conditions improve.
The table below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.
SHOWER | DATE OF MAXIMUM ACTIVITY | CELESTIAL POSITION | ENTRY VELOCITY | CULMINATION | HOURLY RATE | CLASS |
RA (RA in Deg.) DEC | Km/Sec | Local Standard Time | North-South | |||
Dec. Phoenicids (PHO) | Dec 06 | 01:00 (015) -53 | 18 | 20:00 | <1 - <1 | III |
Andromedids (AND) | Nov 09 | 01:28 (022) +55 | 19 | 21:00 | <1 - <1 | III |
Northern Taurids (NTA) | Nov 13 | 05:03 (076) +26 | 29 | 00:00 | 1 – <1 | II |
November Orionids (NOO) | Nov 30 | 06:10 (093) +15 | 44 | 01:00 | 2 – 1 | II |
Geminids (GEM) | Dec 13 | 06:47 (102) +34 | 35 | 02:00 | 1 – <1 | I |
Puppid-Velids (PUP) | Dec 07 | 08:00 (120) -45 | 40 | 03:00 | <1 - 1 | III |
Sigma Hydrids (HYD) | Dec 06 | 08:04 (121) +04 | 61 | 03:00 | 1 – 1 | II |
Dec. Kappa Draconids (DKD) | Dec 03 | 12:17 (184) +71 | 43 | 07:00 | <1 - <1 | IV |