Meteor Activity Outlook for May 9-15, 2009

May is a fairly slow month for meteor activity. The Eta Aquariids are very active the first two weeks 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 1-2 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 full phase on Saturday May 9th. At this time the moon will be present in the sky all night long, making meteor observing difficult at best. Later in the period a window of opportunity for viewing in dark skies will exist during the evening hours between the end of evening twilight and moonrise. Unfortunately rates would still be very low during this time. The estimated total hourly rates for evening observers this week is near one as seen from the northern hemisphere and two for those situated south of the equator. For morning observers the estimated total hourly rates should be near three for those located in the mid-northern hemisphere (45 N) and seven for those viewing from the mid-southern hemisphere (45 S). Locations between these two extremes would see activity between the listed figures. 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. Rates this week are reduced due to the intense moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning May 9/10. 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 full descriptions of each active meteor shower will continue next week when the moon becomes less of a nuisance to observers.

The table below presents a summary of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning but may be used all week.