Almanac · Meteor showers
Eta Aquariids 2025
The Eta Aquariids peaked on Tue 6 May 2025 at 02:51 UTC, when the Earth crossed the thick of the dust from Comet Halley. The Moon was first quarter, 65% lit. The next peak is the Eta Aquariids 2027.
- Peak Solar longitude 45.5°
- Moon at peak 65% lit First Quarter
- Radiant 22h 24m, −01° 00′ Never rises north of 89°N
- Best rate ZHR 50 About 25 an hour at best, from 15°S
Latitude by latitude, the night of 5–6 May
The best hour of the night nearest the peak at each latitude: when the radiant gives the most meteors while the sky is dark, how high it stands then, and how many an hour you would count from a suburban sky (Bortle 5) with that hour’s Moon; a dark site shows more. Times are local solar time; south of 89°S the radiant never sets.
| Latitude | Best hour | Radiant | Moon | Meteors an hour |
|---|---|---|---|---|
| 60°N | — | — | Up, 64% lit | The radiant is below the horizon while it is dark |
| 45°N | 02:31 | 11° up | Down | About 5.9 an hour |
| 30°N | 03:38 | 27° up | Down | About 15 an hour |
| 15°N | 04:14 | 40° up | Down | About 21 an hour |
| 0° | 04:31 | 46° up | Down | About 23 an hour |
| 15°S | 04:55 | 50° up | Down | About 25 an hour |
| 30°S | 05:03 | 45° up | Down | About 23 an hour |
| 45°S | 05:13 | 37° up | Down | About 19 an hour |
Meteor shower The shower
- Zenithal hourly rate at the peak: 50. That is the count for one observer under a perfect sky with the radiant overhead; the table above is what the sky actually gives.
- Parent body: Comet Halley.
- Meteors meet the air at 66 km/s.
- Population index 2.4: each magnitude fainter holds that many times more meteors, which is what moonlight and city light take away.
How we worked it out: the peak is the instant the Sun reaches solar longitude 45.5° (J2000), the shower’s maximum in the International Meteor Organization’s Meteor Shower Calendar, found from Meeus’s solar theory; maxima are broad and wander by hours from year to year. The Moon is Meeus’s lunar theory, the one the map draws, checked against the U.S. Naval Observatory. Each latitude is worked at Greenwich’s longitude for the night nearest the peak, sampled every 10 minutes, and the rate is the IMO’s ZHR turned back into what one observer counts: ZHR × sin(radiant altitude) × r(limiting magnitude − 6.5), with the limiting magnitude the map’s own for that sky and Moon.
- International Meteor Organization, Meteor Shower Calendar (J. Rendtel): each maximum’s solar longitude, ZHR, population index and radiant
- J. Meeus, Astronomical Algorithms, ch. 25 (the Sun) and ch. 47–48 (the Moon), as the map draws them
- U.S. Naval Observatory, Astronomical Applications: the Moon’s illuminated fraction, which the tests hold these to