Meteor Activity Outlook for April 11-17, 2009

Meteor activity picks up a bit during April as two major showers are active during the month. The first of these, the Lyrids, are active from the 16th through the 27th, with a pronounced maximum on the 22nd and 23rd. The Eta Aquariids start appearing near the 27th and reach maximum activity during the first week in May. 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) rise this month toward a maximum in July.

During this period the moon reaches its last quarter phase on Friday April 17th. At this time the moon lies ninety degrees west of the sun and rises near 0100 local daylight time (LDT) The moon remains above the horizon the remainder of the night. This weekend the waning gibbous moon will rise during the early evening hours, spoiling the view the remainder of the night. The estimated total hourly rates for evening observers this week is near two as seen from the northern hemisphere and three for those situated south of the equator. For morning observers the estimated total hourly rates should be near five 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. Meteor rates are reduced this week due to the bright moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning April 11/12. 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.