(meteorobs) Meteor Activity Outlook for August 21-27, 2010

[Robert Lunsford]

Meteor activity kicks into high gear in August as seen from the northern hemisphere. The main reason for this activity surge is the 
Perseid shower that peaks on August 13. This shower is active most of the month and remains above the level of the sporadic 
background for a week centered on August 13. The sporadic activity is also increasing as seen from the northern hemisphere and is 
now nearly double the rates from just three months ago. As seen from south of the equator, meteor rates are still decent but falling 
rapidly. The sporadic rates seen at the beginning of the month will be twice as high as those seen during the last days of the 
month. The Perseid radiant does not rise high into the sky as seen in the southern hemisphere so rates from this shower are greatly 
reduced when compared to the northern hemisphere.

During this period the moon reaches its full phase on Tuesday August 24th. At this time the moon will be located opposite the sun 
and will be in the sky all night long. This weekend the waxing gibbous moon will set near the start of morning twilight, depending 
on your latitude. The further north one is located, the earlier the moon will set, allowing more time to observe under dark skies. 
The estimated total hourly rates for evening observers this week is near two no matter your location. For morning observers the 
estimated total hourly rates should be near eight from the northern hemisphere and six as seen from the 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 this week due to intense 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 August 21/22. 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 table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday 
night/Sunday morning.

The detailed descriptions will be continued next week when the moonlight is not as intense.

August Draconids (AUG) - 18:28 (277) +63    Velocity - 23km/sec.
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr.

Antihelion (ANT) - 22:48 (342) -06   Velocity - 30km/sec.
Northern Hemisphere - 2 per hr.   Southern Hemisphere - 2 per hr.

Delta Aquariids (SDA) - 00:01 (000) -10    Velocity - 42km/sec.
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr.

Perseids (PER) - 04:04 (061) +60   Velocity - 61km/sec.
Northern Hemisphere - 1 per hr.   Southern Hemisphere - <1 per hr.

*For a detailed explanation on the different classes of meteor showers and other astronomical terms, please visit: 
http://www.amsmeteors.org/showers.html#X2010

Clear Skies!
Robert Lunsford
American Meteor Society