Eta Aquariids in 2024 will peak on May 5th
The eta Aquariids are active from April 16 through May 27. The best rates occur from May 1-10 with an added bonus as rates are expected to be enhanced by debris perturbed by Jupiter in a direction closer to the Earth. This last occurred in 2013, when rates were significantly enhanced. We were expecting some enhancement last year but the full moon in early May spoiled efforts to verify this. There will not be any lunar interference this year as the waning crescent moon will not rise until the start of dawn for most locations. Most observers in the northern hemisphere usually see a maximum of 15-20 eta Aquariid meteors per hour under ideal conditions. Those rates could be doubled this year should the enhancement occur.
If you plan to watch for this activity, observing sessions should be undertaken when the radiant lies just below the horizon until the start of civil twilight when the limiting magnitude becomes less than +5.0. This timing is roughly 2:00am local daylight-saving time to 5:00am for observers located at 35 degrees north latitude. The window of opportunity becomes smaller the further north you are located and larger if located further southward. This activity is not visible north of 60 degrees north latitude as the sky does not get sufficiently dark from high northern latitudes this time of year. Observers in the southern tropics have the best viewing opportunity as the nights are longer and the radiant lies higher in the sky prior to dawn. Locations further south will enjoy longer nights, but the radiant elevation actually decreases as one moves southward beyond the southern tropics.
You may be surprised to hear that shower activity can be seen with the radiant located just below the horizon. At this elevation meteors can still skim the upper layers or the atmosphere and will appear as long “earthgrazers”. The condition continues at radiant rise and while the radiant lies low in the sky. As the radiant gains elevation, the meteors are able to penetrate deeper into the atmosphere creating shorter and quicker meteors.
Eta Aquariid rates will be low in April, ranging from one per night on the 16th to perhaps 3 per hour on the 30th. Lunar interference will be significant during the last ten days of April as the moon does not reach its last quarter phase until May 1st. Lunar interference rapidly subsides in early May as the moon wanes from half-illuminated toward new. It would be a good idea during the first days of May to face toward the northeast in order to keep the moon out of your field of view. The strongest activity is expected on the morning of May 5th, but sub peaks on other mornings near this date are not unusual.
As with all meteor showers, it is highly suggested to view from the darkest skies possible as most of the activity is faint. A gain of one magnitude in sky darkness can lead to a doubling of observed meteors. Try to use a lounge chair that allows you to view half-way up in the sky in comfort. Don’t look straight up and most of the activity will be seen in the lower half of the sky. Look high enough to avoid hills and trees that may obscure meteors. Most eta Aquariid meteors will be seen in the eastern half of the sky, which is shown in the chart below. Also note that some meteors will not shoot forth from the eta Aquariid radiant. In early May there is a weak source of activity from Scorpius (Anthelions) plus a half-dozen random meteors each hour not associated with any known shower.
The potential increase in activity may also interest radio meteor scatter observers located in mid-northern latitudes as the radiant lies in a favorable zone in the sky for approximately six hours centered at 08:00. Note that this timing is entirely during daylight this time of year when the meteors cannot be seen visually. This zone is centered at an elevation of 45 degrees above the horizon. Radio rates at higher or lower elevations will be less than when the radiant is located near 45 degrees elevation. For more information on radio meteor scatter visit: https://www.imo.net/observations/methods/radio-observation/
The chart above depicts the sky facing eastward near 4am local daylight-saving time on the morning of May 5th. Drawn in are examples of eta Aquariid meteors shooting outward from the radiant located in the constellation of Aquarius. The easy to see “Great Square” of Pegasus lies just to the left (northward) of the radiant at this time. Also, the bright planet Saturn is just rising directly below the circled radiant.
This year serious observers can help us determine if in fact the eta Aquariids were enhanced in 2024. You simply need to view for at least one hour and estimate your limiting magnitude at the start and end of your session. This is easily done by counting the number of stars visible with certain areas of the sky. Charts for these areas are available at: https://www.imo.net/observations/methods/visual-observation/major/observation/#table1. Area 6 on chart #6 would be the easiest to use. Using more than one area is also encouraged to provide a better estimate over your entire field of view. The conversion table is available in Table 2 on the link provided above. Helpful tips for visual observing are also available at: https://www.imo.net/observations/methods/visual-observation/ and https://www.imo.net/observations/methods/visual-observation/major/observation/. Other important information to record of each meteor is the time, type, and magnitude. In order to submit your observations we suggest that you fill out a visual meteor report form provided by the International Meteor Organization. You must register to provide your data, but there is a free option for those not wishing to subscribe to the IMO Journal. The ALPO Meteors Section also accepts observations emailed directly to: Robert Lunsford
In conclusion, the eta Aquariids will offer a good chance of seeing the strongest activity from this source until the 2040’s. We highly encourage everyone with clear skies to observe during this time and to share your observations. We wish you good luck and look forward to seeing your results!
