American Meteor Society
Eta Aquariids will peak on the mornings of May 4-6 in 2025.
The eta Aquariids are active from April 15 through May 27. The best rates occur during the first week of May when the Earth passes closest to material from Halley’s Comet left behind hundreds of years ago. Recent video data shows that the maximum occurs on May 4th while visual observations point to the morning of the 6th to be the best. It is suggested to watch on all three mornings from May 4-6 to see this shower at its best.There will not be any lunar interference up to May 5th as the waxing gibbous moon will set before the radiant of the eta Aquariids rises. The morning of May 6 is just as good as the 75% illuminated moon will set as the radiant rises. Interference begins on the morning of May 7th as the first hour of eta Aquariid activity will occur with the moon low in the west. On the morning of May 8, only the last hour prior to the start of dawn will be free of moonlight. On the morning of May 9, this window shrinks to only 30 minutes. On the morning of May 10, moon set and dawn are almost simultaneous. These estimates are made for the southern USA. Areas to the north will have less time between the rise of the eta Aquariid radiant and dawn and areas further south will experience more time between radiant rise and the start of dawn.
Most observers in the northern hemisphere usually see a maximum of 10-15 eta Aquariid meteors per hour under ideal conditions in which there is no interference from city lights. 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 02:00 to 04:00 local daylight-saving time for observers located at 45 degrees north latitude. 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.
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.
This 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 for observers in mid-northern latitudes. 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.
We invite you to record data on these meteors and to share it with other observers. 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.
In conclusion, the eta Aquariids will offer a good chance of seeing the strongest meteor activity until late July. 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!
