The Eta Aquariids
Based on NASA, AMS and IMO references, with Moon figures from USNO. Our calculations, suggested observing nights and plain-language guide are labeled separately.
Our guideWhat this means for your night
Our plain-language reading of the sources and calculations on this page. It adds no new facts; the quotes below are the evidence.
What to expect. NASA explains that dust from the same source becomes the Eta Aquariids in May and the Orionids in October. The AMS says this is a strong shower from the southern tropics, but from the equator northward it usually gives only medium rates of 10 to 30 an hour just before dawn. IMO puts the recent ZHR at roughly 40, with ZHRs generally above 30 between May 3 and 10.
Timing. IMO says these meteors are only visible in the hours shortly before dawn, because the radiant culminates near 8h local time. Our calculation agrees: the radiant is highest around 7:30 a.m. local mean solar time, after sunrise. So this is a pre-dawn shower, with no evening option.
Latitude matters. Our radiant table shows why the southern US does better: the radiant reaches about 59° at 30° north but only 41° at 48° north. NASA adds that northern observers more often see Earthgrazers, long meteors that seem to skim the horizon, which is a good reason to watch even when rates are low.
2027 Moon. The Moon is almost absent: USNO shows 1% lit on May 5 and 0% on May 6.
Tips that follow. The AMS describes swift meteors with many persistent trains but few fireballs, and says activity is good for about a week around the maximum, so if the suggested morning is cloudy, try the mornings around it.
| Shower | Night | Published ZHR | Moon lit (USNO, each date) | Radiant highest: our calculation, approximate LMST |
|---|---|---|---|---|
| Eta Aquariids 2027 | May 5–6, 2027 (our suggested night for the Eastern US; IMO gives the maximum as May 6, 2027, 09:00 UT, which our conversion puts at May 6, 5:00 a.m. EDT) | 50 (IMO 2027 calendar) | May 5: waning crescent, 1%; May 6: new moon, 0% | 7:30 a.m. |
LMST is local mean solar time, which can differ from your clock by an hour or more. The time the radiant is highest isn't a recommended start time; it can fall in twilight or daylight. Moon figures: USNO's one-day figure for each calendar date, requested for 39.83° N, 98.58° W (near the center of the contiguous US) at UTC−6. USNO doesn't say what time of day the figure applies to. Illumination only; check local moonrise and moonset.
Where they come from
“The dust grains eventually become the Eta Aquariids in May and the Orionids in October if they collide with Earth's atmosphere.”
Source: NASA meteor shower page
When they're active
“IMO analyses of visual data collected since 1984 have shown that ZHRs are generally above 30 between May 3 and 10.”
Source: IMO 2027 Meteor Shower Calendar (PDF)
“Activity is good for a week centered on the night of maximum activity.”
Source: AMS meteor shower calendar
Where to look
“One of the brightest stars within Aquarius is called Eta Aquarii, and these meteors appear from this area of the constellation.”
Source: NASA meteor shower page
Eta Aquariids: radiant height and rise time, May 5, 2027
Our calculationFrom the radiant position on our calendar: right ascension (RA) 338°, declination (Dec) -1° (IMO 2027 calendar). Method on our About page.
| Latitude | Places near this latitude | Highest altitude | Radiant rises (approximate LMST) |
|---|---|---|---|
| 30° N | Houston, New Orleans | 59° | 1:30 a.m. |
| 40° N | Columbus, Denver | 49° | 1:30 a.m. |
| 48° N | Seattle, northern Minnesota | 41° | 1:30 a.m. |
Highest altitude is when the radiant crosses due north-south. The rise time is when it clears a flat horizon, ignoring refraction, twilight and terrain.
How many to expect
“The Eta Aquariids are a strong shower when viewed from the southern tropics. From the equator northward, they usually produce only medium rates of 10–30 per hour just before dawn.”
Source: AMS meteor shower calendar
“However, the derived ZHR since 2008 (when resonant meteoroids caused high rates) has continuously decreased. The last six years yielded a ZHR level of roughly 40.”
Source: IMO 2027 Meteor Shower Calendar (PDF)
ZHR is a standardized rate: what one observer would count in an hour under a perfectly dark sky with the radiant straight overhead. It isn't a forecast, and what you count is usually lower.
What they look like
“These are swift meteors that produce a high percentage of persistent trains but few fireballs.”
Source: AMS meteor shower calendar
How to watch
“Meteors from this source are only visible in the hours shortly before dawn, as the radiant culminates near 8h local time.”
Source: IMO 2027 Meteor Shower Calendar (PDF)
“In the Northern Hemisphere, Eta Aquariid meteors can more often be seen as "Earthgrazers." Earthgrazers are long meteors that appear to skim the surface of the Earth at the horizon.”
Source: NASA meteor shower page
For any meteor shower
“Most meteor showers are best observed between midnight and dawn.”
Source: AMS meteor FAQ
“Find a dark location with an unobstructed view and give your eyes at least 20–30 minutes to adjust. Full dark adaptation takes longer, so avoid bright lights and phone screens.”
Source: AMS meteor FAQ
“Meteor showers are best observed with the unaided eye. Binoculars and telescopes restrict your field of view, making it harder to catch meteors appearing across the sky.”
Source: AMS meteor FAQ
“Look toward a dark, clear part of the sky, roughly halfway between the horizon and directly overhead.”
Source: AMS meteor FAQ
“It is a standardized estimate of shower activity under ideal conditions: a very dark, clear sky with the radiant directly overhead. It is not the number most observers will actually see.”
Source: AMS meteor FAQ
How many meteors you actually see depends on the shower's activity that night, how dark your sky is, clouds, and how high the radiant is.
We don't know the weather on any given night. Check a forecast, and the calendar for the moon on each date.