Meteor Activity Outlook for May 24-30, 2008

May is a fairly slow month for meteor activity.
The Eta Aquariids are very active the first week of the month then fade as the
month progresses. The only other showers active this month are the Eta Lyrids and
the Antihelion radiant. These will add only 2-3 meteors per hour to the total count.
Sporadic rates are low but steady as seen from the mid-northern hemisphere (45 N).
Sporadic rates seen from the mid-southern hemisphere (45 S) continue to rise this
month toward a maximum in July.

During this period the moon reaches its last quarter
phase on Wednesday May 28th. At this time the moon will be located ninety degrees west
of the the sun and will rise near 0100 local daylight or summer time (DST). This
weekend will prove difficult to view meteoric activity as the waning gibbous moon
will be in the sky most of the night. With the moon rising later each evening
conditions improve as the week progresses. As seen
from the mid-northern hemisphere (45 N) the estimated total hourly rates during the
evening observers would be only one. For morning observers the estimated total hourly
rates should be near six. For those located in the mid-southern hemisphere (45 S)
morning rates would be near fourteen and evening rates near three. 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 reduced due to lunar interference.

The radiant positions and rates listed below are exact
for Saturday night/Sunday morning May 24/25. 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:

The large Antihelion (ANT) radiant is now centered at 17:04 (256) -23. This
area of the sky lies in southern Ophiuchus, eight degrees northeast of the
orange first magnitude star Antares (Alpha Scorpii). Actually any meteor from
northern Scorpius, western Sagittarius, as well as southern Serpens Cauda
could be a candidate for this shower. This radiant is best placed near 0200 LDT
when it lies on the meridian and is highest in the sky. Rates at this time should
be near one for northern observers and two for observers south of the equator.
With an entry velocity of 30 km/sec., the average Antihelion meteor would be of
medium-slow speed.

The Eta Aquariids (ETA) peaked on May 5 and are near the end of their
activity for 2008. Rates are now less than one per hour no matter your location.
Since the radiant lies only sixty degrees west of the sun, meteors from this
shower are not visible prior to 0200 LDT. The radiant is currently located at
23:32 (353) +07. This area of the sky is located in western Pisces near the
fourth magnitude star Theta Piscium. The best time to view this activity is just
before the start of morning twilight, when the radiant lies highest in a dark sky.
No matter your location these meteors will appear from the eastern sky and shoot
in all directions. If the radiant has sufficient altitude Eta Aquariid meteors
can also be seen shooting downward toward the eastern horizon. With an entry
velocity of 66 kilometers per second, a majority of these meteors will appear to
move swiftly with a high percentage of the bright meteors leaving persistent trains.

During late May and early June, an occasional long meteor may shoot upwards from
the northeastern horizon just before dawn. Most likely these are members of the
Daytime Arietid (DAR) meteor shower. The radiant lies approximately thirty
degrees west of the sun therefore only a trace of this shower can ever be seen by
the visual observer. Dawn becomes too bright before the radiant can achieve
sufficient altitude to provide a good display.

If this shower were visible in a dark sky it would be among the strongest displays
of the year. This shower is the strongest daylight/radio shower of the year. The
current position of the radiant is 02:20 (035) +16. This position lies in western
Aries, seven degrees southeast of the second magnitude star Hamal (Alpha Arietis).
Seeing any activity from this display would be extremely lucky this week. Prospects
improve as we approach the June 7 maximum.

As seen from the mid-northern hemisphere (45N) the Sporadic rates are
low, but fairly steady. One would expect to see approximately five random meteors
during the last hour before dawn from rural observing sites and only one per hour
during the evening hours. As seen from the mid-southern hemisphere (45S) morning
rates would be near twelve per hour as seen from rural observing sites and three
per hour during the evening hours. Moonlight interferes during the morning hours.

The table below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.