2008 Meteor Shower Calendar
| Shower | Activity Period | Maximum | Radiant | Velocity | r | ZHR | Class | Moon | ||
|---|---|---|---|---|---|---|---|---|---|---|
| Date | S. L. | R.A. | Dec. | km/s | ||||||
| Antihelion Source (ANT) | Nov 25-Sep 30 | - | - | - | - | 30 | 3.0 | 3 | II | - |
| Quadrantids (QUA) | Jan 01-Jan 05 | Jan 04 | 283°16 | 15:20 | +49° | 41 | 2.1 | 120 | I | 25 |
| Alpha Centaurids (ACE) | Jan 28-Feb 21 | Feb 08 | 319°2 | 14:00 | -59° | 56 | 2.0 | 5 | II | 1 |
| Delta Leonids (DLE) | Feb 15-Mar 10 | Feb 25 | 336° | 11:12 | +16° | 23 | 3.0 | 2 | II | 18 |
| Gamma Normids (GNO) | Feb 25-Mar 22 | Mar 13 | 353° | 16:36 | -51° | 56 | 2.4 | 4 | II | 6 |
| Lyrids (LYR) | Apr 16-Apr 25 | Apr 22 | 032°32 | 18:04 | +34° | 49 | 2.1 | 18 | I | 16 |
| Pi Puppids (PPU) | Apr 15-Apr 28 | Apr 23 | 033°5 | 07:20 | -45° | 18 | 2.0 | var | III | 17 |
| Eta Aquarids (ETA) | Apr 19-May 28 | May 05 | 045°5 | 22:32 | -01° | 66 | 2.4 | 60 | I | 0 |
| Eta Lyrids (ELY) | May 03-May 12 | May 08 | 048.4° | 19:08 | +44° | 44 | 3.0 | 3 | II | 3 |
| June Bootids (JBO) | Jun 22-Jul 02 | Jun 27 | 095°7 | 14:56 | +48° | 18 | 2.2 | var | III | 22 |
| Piscis Austrinids (PAU) | Jul 15-Aug 10 | Jul 27 | 125° | 22:44 | -30° | 35 | 3.2 | 5 | II | 23 |
| Delta Aquarids (SDA) | Jul 12-Aug 19 | Jul 27 | 125° | 22:36 | -16° | 41 | 3.2 | 20 | I | 23 |
| Alpha Capricornids (CAP) | Jul 03-Aug 15 | Jul 29 | 127° | 20:28 | -10° | 23 | 2.5 | 4 | II | 25 |
| Perseids (PER) | Jul 17-Aug 24 | Aug 12 | 140° | 03:04 | +58° | 59 | 2.6 | 100 | I | 11 |
| Kappa Cygnids (KCG) | Aug 03-Aug 25 | Aug 17 | 145° | 19:04 | +59° | 25 | 3.0 | 3 | II | 15 |
| Alpha Aurigids (AUR) | Aug 25-Sep 08 | Aug 31 | 158°6 | 05:36 | +42° | 66 | 2.6 | 7 | II | 1 |
| September Perseids (SPR) | Sep 05-Sep 16 | Sep 09 | 166°7 | 04:00 | +47° | 64 | 2.9 | 5 | II | 9 |
| Delta Aurigids (DAU) | Sep 18-Oct 10 | Oct 03 | 191° | 05:52 | +49° | 64 | 2.9 | 2 | II | 3 |
| Draconids (GIA) | Oct 06-Oct 10 | Oct 08 | 195°4 | 17:28 | +54° | 20 | 2.6 | var | III | 8 |
| Epsilon Geminids (EGE) | Oct 14-Oct 27 | Oct 18 | 205° | 06:48 | +27° | 70 | 3.0 | 2 | II | 18 |
| Orionids (ORI) | Oct 02-Nov 07 | Oct 21 | 208° | 06:20 | +16° | 66 | 2.5 | 23 | I | 21 |
| Leo Minorids (LMI) | Oct 23-Oct 25 | Oct 24 | 211° | 10:48 | +37° | 61 | 2.7 | 2 | II | 24 |
| Southern Taurids (STA) | Oct 01-Nov 25 | Nov 05 | 223° | 03:28 | +13° | 27 | 2.3 | 5 | II | 6 |
| Northern Taurids (NTA) | Oct 01-Nov 25 | Nov 12 | 230° | 03:52 | +22° | 29 | 2.3 | 5 | II | 13 |
| Leonids (LEO) | Nov 10-Nov 23 | Nov 17 | 235°27 | 10:12 | +22° | 71 | 2.5 | var | III | 18 |
| Alpha Monocerotids (AMO) | Nov 15-Nov 25 | Nov 21 | 239°32 | 07:48 | +01° | 65 | 2.4 | var | III | 23 |
| Dec Phoenicids (PHO) | Nov 28-Dec 09 | Dec 06 | 254°25 | 01:12 | -53° | 18 | 2.8 | var | III | 8 |
| Puppid/Velids (PUP) | Dec 01-Dec 15 | Dec 06 | 255° | 08:12 | -45° | 40 | 2.9 | 10 | I | 8 |
| Monocerotids (MON) | Nov 27-Dec 17 | Dec 08 | 257° | 06:40 | +08° | 42 | 3.0 | 2 | II | 10 |
| Sigma Hydrids (HYD) | Dec 03-Dec 15 | Dec 11 | 260° | 08:28 | +02° | 58 | 3.0 | 3 | II | 13 |
| Geminids (GEM) | Dec 07-Dec 17 | Dec 13 | 262°2 | 07:28 | +33° | 35 | 2.6 | 120 | I | 15 |
| Coma Berenicids (COM) | Dec 12-Jan 23 | Dec 20 | 268° | 11:40 | +25° | 65 | 3.0 | 5 | II | 22 |
| Ursids (URS) | Dec 17-Dec 26 | Dec 22 | 270°7 | 14:28 | +76° | 33 | 3.0 | 10 | I | 24 |
The meteor showers discussed below recur each year; in some cases they have been recognized for hundreds of years. The name of the shower in most cases indicates the constellation from which the meteors appear. Also discussed are sporadic rates. Sporadic meteors are those random meteors not associated with a particular shower; they are the random detritus left over from the creation of the solar system or are old dispersed debris not recognizable today as shower meteors. Click on the shower names (when linked) for more detail on any given shower. For meteor observers, those located in the northern hemisphere have a distinct advantage as shower activity is stronger there than that seen by observers located south of the equator. The reason for this is that most of the major showers have meteors that strike the Earth in areas located far above the equator. As seen from the northern hemisphere these meteors would appear to rain down from high in the sky in all directions. From those situated in the southern hemisphere only a small percentage of this activity is visible. Any activity would appear to travel upwards from radiants located low in the sky.
There are a few meteor showers best seen from the southern hemisphere. These would include any radiant with a declination (celestial latitude) below -20 and those that reach maximum activity during the southern hemisphere's winter months (July-August-September). These showers would include the Alpha Centaurids, Gamma Normids, Pi Puppids, Piscis Austrinids, Delta Aquarids, Alpha Capricornids, Dec Phoenicids, and the Puppid/Velids.
The year begins with the intense but brief Quadrantid maximum (January 3/4). Its brevity combined with typically poor winter weather hampers observation. January overall has good meteor rates restricted to the last third of the night. Rates to 20/hour can be obtained. A large number of radiants spread along the ecliptic from Cancer to Virgo. This activity diminishes somewhat in February with the same areas active.
Late-night rates are fair in the first half of March, but become poor rather suddenly after mid-March. The very poor rates, seldom reaching 10/hour, continue into early June. However, two major showers appear in this interval. The Lyrids past mid-April (max: April 21/22) raise meteor rates for several nights. The Eta Aquarids (max: May 5/6) enrich late nights of May's first half, sometimes substantially.
February, March, and April evenings have another notable feature. An unusual number of sporadic fireballs come in this interval, possibly one every few nights.
June to mid-July has fair rates. The last half of July has rates increasing steadily as the Delta Aquarids (July 27/28) and Alpha Capricornids (July 30 - August 1) have maxima at month's end. Even the Perseids are beginning to show a little.
Overall, late July to mid-August is very rich in meteors. The Perseid maximum, just before mid-August (August 12/13), is fairly prolonged and quite rich.
High sporadic activity after midnight continues for the rest of the year, but especially in September and the first half of December. Sporadic rates over 20/hour are possible for this entire interval. September radiants are numerous in Aries and Taurus.
Mid-October to mid-December is a nearly continuous period of heavy meteor activity. The Orionids (max: October 21/22) during the second half of October have a prolonged, plateau maximum for several nights, usually rich. The Taurids (max: November 5/6 for S. Taurids, November 11/12 for N. Taurids), active for two months, are most numerous in November's first half, and can be rather variable in strength. This period is the best for a couple of Taurid fireballs each night, if the shower is not too weak. The Leonids of mid-November (max: November 17-19) are quite unpredictable, with rich displays occuring roughly every 33 years. The last Leonid storm period occurred from 1998 through 2002. The next enhancement for the Leonids is predicted in 2006, when rates may approach 60/hr. for a short time. Studies have shown that no Leonid storms will occur in either 2033 or 2066. We will have to wait until 2099 for a return of the activity recently seen during the past few years.
Finally the Geminids of mid-December (max: December 13/14) climax the year with the strongest dependable and observable display. Geminid rates usually pass 60-70/hour at maximum. Concurrent activity from Leo and Canis Minor is also notable during the Geminids. Finally, the oft-overlooked Ursids complete the year's activity, reaching maximum on December 21/22. Nearly half the year's visual meteor activity is crammed into the two-month interval just described.
Explanation of the 2008 Meteor Shower Calendar
Shower: named for the constellation or closest star within a constellation where the radiant is located at maximum activity.
Activity Period: the dates when the ZHR (Zenith Hourly Rates) are equal to or greater than one.
Maximum: the date on which the maximum activity is expected to occur.
S.L.: the equivalent solar longitude of the date of maximum activity. Solar longitude is measured in degrees (0-359) with 0 occurring at the exact moment of the spring equinox, 90 at the summer solstice, 180 at the autumnal equinox, and 270 at the winter solstice.
Radiant: the area in the sky where shower meteors seem to appear from. This position is given in right ascension (celestial longitude) and declination (celestial latitude).
Velocity: the velocity at which shower meteors strike the Earth's atmosphere. The velocity depends on the angle meteoroids (meteors in space) intersect the Earth. Meteoroids orbiting in the opposite direction of the Earth and striking the atmosphere head-on are much faster than those orbiting in the same direction as the Earth. This speed is measured in kilometers per second.
r: The Population Index, An estimate of the ratio of the number of meteors in subsequent magnitude classes. Simply stated: the lower the "r" value, the resulting overall mean magnitude of each shower will be brighter. "r" usually ranges from 2.0 (bright) to 3.5 (faint).
ZHR: Zenith Hourly Rate, the average maximum number of shower meteors visible per hour if the radiant is located exactly overhead and the limiting magnitude equals +6.5. Actual counts rarely reach this figure as the zenith angle of the radiant is usually less and the limiting magnitude is usually lower. ZHR is a useful tool when comparing the actual observed rates between individual observers as it sets observing conditions for all to the same standards.
Class: A scale developed by Robert Lunsford to group meteor showers by their intensity:
Class I: the strongest annual showers with ZHR's normally ten or better.
Class II: reliable minor showers with ZHR's normally three or better.
Class III: showers with widely variable rates. They may be strong one year and totally inactive the next.
Class IV: weak minor showers with ZHR's rarely exceeding three. The study of these showers is best left to experienced observers who use plotting and angular velocity estimates to determine shower association. Observers with less experience are urged to limit their shower associations to showers with a rating of I to III. These showers are also good targets for video and photographic work.
Moon: the age of the moon in days where 0 is new, 7 is first quarter, 14 is full, and 21 is last quarter. Meteor activity is best seen in the absence of moonlight so showers reaching maximum activity when the moon is less than 10 days old or more than 25 are much more favorably observed than those situated closer to the full moon.