Almanac · Meteor showers
Delta Aquariids 2025
The Delta Aquariids peaked on Thu 31 Jul 2025 at 07:13 UTC, when the Earth crossed the thick of the dust from Comet 96P/Machholz. The Moon was first quarter, 39% lit. The next peak is the Delta Aquariids 2027.
- Peak Solar longitude 128°
- Moon at peak 39% lit First Quarter
- Radiant 22h 40m, −16° 24′ Never rises north of 73.6°N
- Best rate ZHR 25 About 16 an hour at best, from 15°S
Latitude by latitude, the night of 30–31 Jul
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 73.6°S the radiant never sets.
| Latitude | Best hour | Radiant | Moon | Meteors an hour |
|---|---|---|---|---|
| 60°N | 02:05 | 14° up | Down | About 3.8 an hour, in twilight that never ends |
| 45°N | 02:05 | 29° up | Down | About 7.6 an hour |
| 30°N | 02:04 | 44° up | Down | About 11 an hour |
| 15°N | 02:07 | 59° up | Down | About 14 an hour |
| 0° | 02:02 | 74° up | Down | About 15 an hour |
| 15°S | 02:03 | 89° up | Down | About 16 an hour |
| 30°S | 02:09 | 76° up | Down | About 15 an hour |
| 45°S | 02:06 | 61° up | Down | About 14 an hour |
Meteor shower The shower
- Zenithal hourly rate at the peak: 25. 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 96P/Machholz.
- Meteors meet the air at 41 km/s.
- Population index 2.5: 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 128° (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